Topics
Electronic
Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active devices to control electron flow by amplification and rectification, which distinguishes it from classical electrical engineering which uses passive effects such as resistance, capacitance and inductance to control current flow.
Electronics has had a major effect on the development of modern society. The identification of the electron in 1897, along with the subsequent invention of the vacuum tube which could amplify and rectify small electrical signals, inaugurated the field of electronics and the electron age. This distinction started around 1906 with the invention by Lee De Forest of the triode, which made electrical amplification of weak radio signals and audio signals possible with a non-mechanical device. Until 1950, this field was called "radio technology" because its principal application was the design and theory of radio transmitters, receivers, and vacuum tubes.
Computer
A computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve, and process data. You may already know that you can use a computer to type documents, send email, play games, and browse the Web. You can also use it to edit or create spreadsheets, presentations, and even videos.
A computer consists of four major parts: the input, output, CPU (central processing unit), and memory.
Input consists of anything you will add into the computer (microphone, keyboard, mouse, scanner), and output is how the computer gives back to you (think screen, speakers, etc.). The CPU or central processing unit is located on the motherboard and is the part of the computer where all that input/output information gets sent to the proper place. Memory, commonly referred to as RAM (random access memory), as you may already know, is where the information is stored.
Computer Hardware
Any physical device or equipment used in or with a computer system (anything you can see and touch).
The computer hardware components are the physical parts of the computer system. The computer hardware includes the electronic, electrical and mechanical components connected to the computer system.
Hardware components can be of two types. Some hardware components are placed inside the computer system case (cabinet) and the peripheral hardware devices are connected externally to the system.
Computer hardware is the physical collection of elements that complete a whole computer system. Hardware encompasses the external tools that allow users to operate a computer, such as the keyboard and mouse, outer elements of the machine such as the monitor, and internal components like the motherboard, graphics card, and data storage.
Input device – a piece of hardware device which is used to enter information to a computer for processing. e.g. keyboard, mouse, trackpad (or touchpad), touchscreen, joystick, microphone, light pen, webcam, speech input, etc.
Output device – a piece of hardware device that receives information from a computer. e.g. monitor, printer, scanner, speaker, display screen (tablet, smartphone …), projector, head phone, etc.
Internal hardware devices (or internal hardware components) – any piece of hardware device that is located inside the computer. e.g. CPU, hard disk drive, ROM, RAM, etc.
Computer Network
Computer Network means an interconnected collection of autonomous computers. Two or more computers are connected to each other using cable or without using cable (Wireless) is known as computer network. A computer that facilitates the sharing of data, software and hardware resources on the network, is termed as a server and other computer in same network termed as client.
Servers are computers that hold shared programs, files, and the network operating system. Servers allow access to network resources to all the users of the network.
Clients are computer devices which access and uses the network as well as shares network resources. They are also users of the network, as they can send and receive requests from the server.
Types of networks:
- Local Area Networks (LANs): Small computer networks that are confined to a localised area (e.g. an office, a buildeing) are known as LANs.
- Metropolitan Area Networks (MANs):Networks that spread over a city (e.g. Cable TV networks) can be termed as MANs.
- Wide Area Networks (WANs): The networks spread across countries are known as WANs. A WAN is a group of computer networks that are separated by large distances and tied together. It can even be a group of LANs, MANs that spread across seeral locations.
Transmission media(Channel) is a carrier used to interconnect computers in a network, such as Twisted Pair Cable, Coaxial Cable, Optical Fibre.... It is also known as links, channels, or lines.
Software
Software – a set of instructions or programs that tells a computer what to do or how to perform a specific task (computer software runs on hardware). A software is a means of communication between computer system and computer user. The software is a kind of programs that enable a user to perform some specific task or used to operate a computer.
Main types of software: Systems software and Application software.
System Software:
System software is used by system itself to communicate the hardware components. These software aids the user and the hardware to function and interact with each other. Basically, it is a software to manage computer hardware behavior so as to provide basic functionalities that are required by the user.
The system software is a type of computer software that is designed for running the computer hardware parts and the application programs. It is the platform provided to the computer system where other computer programs can execute. The system software act as a middle layer between the user applications and hardware. The operating system is the type of system software.
Operating System: The operating system is used to manage all other programs installed on the computer. It is the most prominent example of System Software. The operating system is the software that allows you to operate the hardware. The programs that we want to execute, the applications that we want to use all require a platform on which to execute. That platform is provided by the operating system.
It is a collection of software that handles resources and provides general services for the other applications that run over them. Although each Operating System is different, most of them provide a Graphical User Interface through which a user can manage the files and folders and perform other tasks. Every device, whether a desktop, laptop or mobile phone requires an operating system to provide the basic functionality to it. As an OS essentially determines how a user interacts with the system, therefore many users prefer to use one specific OS for their device. There are various types of operating system such as real-time, embedded, distributed, multiuser, single-user, internet, mobile, and many more. It is important to consider the hardware specifications before choosing an operating system.
Application Software
Application software provides a specific functionality to the user. These softwares provide user friendly interface to the user to operate the computer for intended purpose. It is capable of dealing with user inputs and helps the user to complete the task.
Application software may consist of a single program, such as Microsoft's notepad for writing and editing a simple text. It may also consist of a collection of programs, often called a software package, which work together to accomplish a task, such as a spreadsheet package.
Application software tends be used for the tasks that have some relationship to the world outside of the computer. For example, you might use a word processor to write a letter or an essay. Although you use the computer to perform the task, the task itself might reasonably be considered to be a non-computer task.
Application Software, also known as end-user programs are software that helps the user in completing tasks such as doing online research, jotting down notes, setting an alarm, designing graphics, keeping an account log, doing calculations or even playing games. They lie above the system software. Unlike system software, they are used by the end-user and are specific in their functionality or tasks and do the job that they are designed to do.
The difference between system software and application software is the difference in the user interface. In system software, there is no user interface present whereas in application software the user interface is present for each software so that users can easily use the software. The user cannot see the system software like an operating system and cannot work in system software but in an application, software users can see the application software using a graphical user interface and can also work in the application software. The user also has an option to create its user-written software and use the software for its personal use.
The programming language is the third category of computer software which is used by the programmers to write their programs, scripts, and instructions which can be executed by a computer. The other name of the programming language is a computer language that can be used to create some common standards. The programming language can be considered as a brick which can be used to construct computer programs and operating system. The examples of programming languages are JAVA, C, C++, and other languages.
Internet:
INTERNET stands for Interconnected Network that is a network system that connects millions of web servers. Internet is a global network of networks. It is a global computer network providing a variety of information and communication facilities, consisting of interconnected networks using standardized communication protocols. Internet is a means of connecting a computer to any other computer anywhere in the world. The internet is a globally connected network system facilitating worldwide communication and access to data resources through a huge collection of personal, public, business, academic and government networks. The first version of the Internet was known as ARPANET. Internet uses IP address. Internet is superset of WWW.
Internet is made up of millions of computers all over the world that are digitally connected to each other by cable, fibre or wireless links. You can use the internet to browse websites, communicate with people, download pictures and videos, listen to music or do lots of other amazing things.
To know more about How does internet works?
An intranet is a computer network for sharing information, collaboration tools, operational systems, and other computing services within an organization, usually to the exclusion of access by outsiders. An intranet is a private network. Usually intranet is not used as a term for home networks, but technically every LAN is an intranet, or part of one. An intranet doesn't have to be local, it can be the private network of a company with 3 offices which are all linked up with a Wide Area Network.
WWW (World Wide Web):
It was invented in 1989 by Tim Berners-Lee at CERN, Geneva, Switzerland. WWW is a subset of the Internet. WWW uses HTTP. The World Wide Web commonly referred to as WWW or just the Web is an interconnected system of public webpages accessible through the Internet. The Web is not the same as the Internet: the Web is one of many applications built on top of the Internet. The www is the part of the Internet that contains websites and webpages. Websites are composed of pages linked by hypertext links that are written in HTML. The software to see the World Wide Web is called a web browser. WWWW is a group of Internet sites interconnected by means of hypertext, providing access to images and sound in addition to text.
What is HTTP:
HTTP is the set of rules that control the way data is sent and received over the internet. It is a protocol used to request and transmit files, especially webpages and webpage components, over the internet or other computer network. "Hyper Text Transport Protocol" - HTTP is the single most important technology that drives the web and yet remains virtually transparent. Without this protocol HTML and XML via the web would not be able to perform the myriad of tasks that we put them to daily. Hyper means digital text that contains hyperlinks to other texts. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access. The HTTP is the method used to transfer Web pages to your computer. With hypertext, a word or phrase can contain a link to another Web site. All Web pages are written in the hyper-text markup language (HTML), which works in conjunction with HTTP. HTTP is a protocol run over TCP with all the features necessary for interacting with web servers that hold text and binary resources.
Asynchronous Protocol: Asynchronous means "not at the same time". This is the basis of the request-response architecture of HTTP.
A request is issued and the response will return some time later. The web browser will not wait for the response actively, instead it will leave the line of communication to the server open until the response or a timeout occurs. It is important to note that it is request-response from the client web browser. A server cannot send unsolicited responses. There are however web-push technologies that are not discussed here. A web browser is configured to have no more than two outstanding requests open concurrently. This is defined in the HTTP specification and is designed to prevent overloading of the server by any single individual.
The Request The most frequently used requests are GET and POST. The GET fetches a resource from the web server using a path, not a fully qualified URL as the server is implicitly the second party in the communication.
The Response The response consists of a header and body just like the request. The header contains a status code and the body contains the resource.
HTML
Hypertext Markup Language(HTML), a standardized system for tagging text files to achieve font, colour, graphic, and hyperlink effects on World Wide Web pages. The first version of HTML was written by Tim Berners-Lee in 1993. Since then, there have been many different versions of HTML. HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScript. Web browsers receive HTML documents from a web server or from local storage and render the documents into multimedia web pages. HTML describes the structure of a web page semantically and originally included cues for the appearance of the document.
- HTML is the standard markup language for creating Web pages
- HTML describes the structure of a Web page
- HTML consists of a series of elements
- HTML elements tell the browser how to display the content
- All HTML documents must start with a document type declaration: .
- The HTML document itself begins with and ends with .
- The visible part of the HTML document is between and .
Domain & SubDomain, URL
Domain :
Domain Registration
The unique name that identifies an Internet site. Domain Names always has 2 or more parts, separated by dots. When you register a domain name, your address, e-mail and phone number are published in the public WHOIS database. ICANN requires this personal information to be available for anybody to view on the web. Associating a specific server with a name that's easy to remember simplifies Internet navigation for us. It's much easier to remember Company.com than a server name, and simplifies the job for the website provider as well.
Domain names are controlled by a handful of companies, known as registrars, appointed by ICANN (Internet Corporation for Assigned Names and Numbers), and domain names are held in a master database maintained by InterNIC (Internet Network Information Center). You obtain a domain name by applying for it through a registrar and paying a fee.
Subdomains :
Subdomains are the third level domains that are used to organize your web site content. They are just like folders under your root directory. But they will have a special URL to access. Your host should enable subdomain creating feature for you. Number of subdomains that are alloted for you depends on the type of hosting plan you are using. You can use ’subdomains’ icon or text link in your control panel to create, delete and edit your subdomains.
http://www.yoursitename.com is the regular URL without a subdomain.
http://product.yoursitename.com is an URL with subdomain "product".
Here the:
.com is the first level domain
yoursitename is the second level domain
product is the third level domain
What is the purpose of subdomains?
1. You can organise your web site like support and FAQ at 'http://support.yoursitename.com' And under 'http://faq.yoursitename.com' etc.
2. You can also organise the email addresses that comes to seperate departments on your web site like support@support.yoursitename.com, orders@store.yoursitename.com etc.
3. Long URLs are cut short to a subdomain, so it is easy to remember the short URL instead of long URLs.
URL (Uniform Resource Locator ) :
The URL instructs your browser exactly where to go and what to do when it gets there using a specific protocol, server, and document. The most common protocol is "http://", (hypertext transfer protocol), or "https://" if the document is on a secure server.
A, URL, or Web address, is a standardized address name layout for some resource (such as a document or image) on the Internet. It provides the address for locating information on the Internet.
- The major difference between a domain name and a URL are relatively simple to express. Essentially the domain name is the overall name of the website while the URL is the extended path.
Consider this... you want a website, so you go out and purchase a website name from a registrar, this would be your domain name. If you however decided that you want a website and you get it from say Geocities, and your website is a part of geocities, the link you have is your URL.
Domain : http://www.yourdomain.com
Subdomain : http://subdomain.yourdomain.com
URL : http://www.somedomain.com/your - It is a directory (folder) within the domain.
Web Page : http://www.yourdomain.com/test/index.htm
In the above situation, the yourdomain.com is the domain. For the url, it is everything that comes with the http:// all the way to the end. Generally a domain has more importance, than the sub domains or url, however a sub domain has more importance than the url does individually.
It was suggested that .com be used primarily for commercial businesses, .net for network related organizations and .org for nonprofit groups. This quickly became unworkable and consequently, in the case of .com, .net and .org. In fact, many registrants order their domain name as .com, .net and .org. .com, .net and .org are unrestricted open domains.
- .info is the internet's first unrestricted top level domain since .com Around the globe, .info is synonymous with information. .info allows you to protect your brand, expand your global presence, and drive more traffic to your site. Anyone can register a .info.
- .biz is the internet's first top level domain just for businesses - the new and visionary domain that will compliment, enhance, and extend how you do business on the Internet. .biz is an open domain.
- .us is for individuals or companies. Any US citizen or company can register a .us domain.
- .asia is for individuals or companies. Enhance your Asian presence with a .asia domain.
- .co.uk is for companies for United Kingdom.
- .in is for India.
- .co.in is for commercial entities for India.
- .net.in is for network entities for India.
- .org.in is for nonprofit organizations for India.
- .firm.in is for firm or company for India.
- .gen.in is for general use for India.
- .ind.in is for individual for India.
- .cc is an open domain (Cocos (Keeling) Islands).
- .edu Formerly, the .edu domain was reserved for 4-year, degree-granting colleges and universities. Now, Eligibility for a .edu domain name is limited to regionally-accredited, degree-granting institutions of higher education that are accredited by one of the six U.S. regional accrediting agencies. Each such institution may hold only a single name in the .edu domain. This change means that community colleges, are now eligible for .edu names.
Web hosting :
Windows Hosting Plans- The collection of all your web pages is called your web site.
- To let others view your web pages, you must publish your web site.
- To publish your work, you must copy your site to a web server.
- Most common is to use an Internet Service Provider (ISP).
- ISP stands for Internet Service Provider.
- Web hosting means storing your web site on a public server.
- Web hosting normally includes email services.
- Web hosting often includes domain name registration.
A web hosting service is a type of Internet hosting service that allows individuals and organizations to make their own website accessible via the World Wide Web.
Providing space on Internet servers for the storage of World Wide Web sites which can be accessed by others through the network. This service is usually offered by ISPs or web hosting specialists.
Web hosting is often provided as part of a general Internet access plan; there are many free and paid providers offering these A customer needs to evaluate the requirements of the application to choose what kind of hosting to use. Such considerations include database server software, scripting software, and operating system.
A term used for storing and maintaining files, email or domains on a server that is connected with Internet.
Types of hosting :
Free Hosting : Just about all the free web hosting available is extremely limited when compared to paid hosting. Free web hosts generally require their own ads on your site, only allow web-based uploading and editing of your site, and have very tight disk space and traffic limits. Still, most people get their start via free web hosting.
Dedicated Server Hosting : A dedicated hosting service, dedicated server, or managed hosting service is a type of Internet hosting in which the client leases an entire server not shared with anyone. This is more flexible than shared hosting, as organizations have full control over the server(s), including choice of operating system, hardware, etc. Server administration can usually be provided by the hosting company as an add-on service. In some cases a dedicated server can offer less overhead and a larger return on investment.
With dedicated hosting, one gets a server of one's own. They have no restrictions, except for those designed to maintain the integrity of the Web host's network (for instance, banning sites with adult content due to the increase risk of attack by hackers and grey legal issues for the ISP). Unless a separate plan is purchased from the host, the user is also generally on his own. This can be an expensive proposition, as the purchase of the dedicated server itself is generally far more expensive compared to shared hosting.
Shared hosting : A shared web hosting service or virtual hosting service or derive host refers to a web hosting service where many websites reside on one web server connected to the Internet. Each site "sits" on its own partition, or section/place on the server, to keep it separate from other sites. This is generally the most economical option for hosting, as many people share the overall cost of server maintenance. one's Web site is placed on the same server as several hundred other sites. A problem with another site on the server can bring all of the sites down. Shared hosting also brings with it some restrictions regarding what exactly can be done, although these restrictions are nowhere near as restrictive as for free hosting.
In general shared hosting will be inappropriate for users who require extensive software development outside what the hosting provider supports. Almost all applications intended to be on a standard web server work fine with a shared web hosting service. But on the other hand, shared hosting is cheaper than other types of hosting such as dedicated server hosting. Shared hosting usually has usage limits and most hosting providers have extensive reliability features in place.
Virtual private server (VPS) Hosting : VPS is a marketing term used by Internet hosting services to refer to a virtual machine for use exclusively by an individual customer of the service. The term is used to emphasize that the virtual machine, although running in software on the same physical computer as other customers' virtual machines, is functionally equivalent to a separate physical computer, is dedicated to the individual customer's needs, has the privacy of a separate physical computer, and can be configured to run as a server computer (i.e. to run server software). The term Virtual Dedicated Server or VDS is used less often for the same concept.
Each virtual server can run its own full-fledged operating system and can be independently rebooted. The practice of partitioning a single server so that it appears as multiple servers has long been common practice on mainframe computers and mid-range computers such as the IBM AS/400. It has become more prevalent with the development of virtualization software and technologies for microcomputers.
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Each VPS performs and executes exactly like a stand-alone server for its users and applications as it can be rebooted independently and has its own root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files.
Features and Benefits of VPS
- VPS performs and executes exactly like an isolated stand-alone server.
- Provides a cheaper, secure and easier alternative to dedicated.
- VPS runs off-the-shelf software without any changes.
- Root access & Easy to use control panel.
- Allows Customized application set and flexibility of installing any application
Cursor :
When you use a computer which has a graphical user interface, the operating system uses a cursor to show the current position of the mouse pointer. A cursor is a graphical image that usually represents an object illustrating the operation that can be performed by the mouse action.
In its normal state the cursor is a simple arrow. However, when you move the mouse pointer over the screen, the cursor may change with the context.
The cursor on your screen can indicate two things: 1) where your mouse pointer is, or 2) where the next character typed will be entered in a line of text.
A cursor is a movable indicator that is used to indicate the current position for any input on a computer interface. The cursor can be moved along the interface or application with the help of various keys on the keyboard or with the help of input or pointing devices such as a mouse. A cursor helps users to select actions such as drag, drop, click and point in specific applications and also helps in text entry in the case of text-based interfaces.
The mouse cursor is most often an arrow that you can use to point to different objects on your screen. When the cursor is over an object, you can click or double-click the mouse button to perform an action on that object (such as opening a program). The mouse cursor can change into other images, such as a small hand (when you roll over a link in a Web page), or an hourglass (when Windows is "thinking" so hard, it won't let you click on anything).
The text cursor is typically a straight vertical line or I-shaped object that flashes in a line of text. In the case of text editors or command-line interfaces, the cursor is known as a caret or text cursor. Typically, when you are typing a paper, the cursor will be at the end of the line, because you are adding new text to the uncharted white area of the page. However, if you want to insert a word or phrase somewhere else in a line of text, you can use the mouse cursor to click the position where you would like to insert the text. In most word processing programs, once you start typing, the text cursor continues to flash, but the mouse pointer disappears until you move the mouse again. This is to avoid "cursor confusion," since most people can't type and click on things at the same time.
In computer user interfaces, a cursor is an indicator used to show the current position for user interaction on a computer monitor or other display device that will respond to input from a text input or pointing device. The mouse cursor is also called a pointer, owing to its resemblance in usage to a pointing stick.
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