Basics of Internet

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Introduction to Internet
The Internet is a worldwide collection of interconnected computer networks that enables businesses, organizations, governments, and individuals to communicate in a variety of ways. One of the most popular ways users communicate on the Internet is by publishing and interacting with Web pages. You can also use the Internet to send and receive e-mail, chat with other users, and transfer files between computers.

Internet Explorer

Types of Connections

Users connect to the Internet through a variety of methods. A relatively inexpensive but slow way to connect is with dialup service, which involves using a modem and a phone line. Faster ways to connect include DSL (digital subscriber line), cable modem, satellite, and ISDN (integrated services digital network). Networks include special wireless transmitters that allow computers to access the Internet wirelessly. Companies that help you connect to the Internet are known as Internet service providers, or ISPs.

Connection Speeds 
Connection speeds play an important part in a user’s Internet experience because slower connections result in slower file transfers and Web page viewing. Dialup connections offer the slowest access to the Internet at up to 56 kilobits per second, or Kbps, followed by ISDN connections at 64 to 128 Kbps. DSL usually offers connection speeds of up to 3 megabits per second, or Mbps, while cable modems can achieve speeds of up to 6 Mbps. A Web page that takes about 20 seconds to download via dialup can take less than a second using a cable modem.

Communication Standards
The Internet infrastructure relies on a variety of protocols that dictate how computers and networks talk to each other. For example, Transmission Control Protocol/Internet Protocol, or TCP/IP, is a set of rules that control how Internet messages flow between computers. Hyper Text Transfer Protocol, or HTTP, is a set of rules that determine how browsers should request Web pages and how server computers should deliver them. Having agreed-upon protocols allows seamless communication among the many different types of computers that connect to the Internet.

The World Wide Web 
The World Wide Web is a giant collection of documents, or pages, stored on computers around the globe. Commonly called the Web, this collection of pages represents a wealth of text, images, audio, and video available to anyone with a computer and an Internet connection. Web pages are stored on servers, which are Internet-connected computers running software that allows them to serve up information to other computers. When you place a text file, image, or other document in a special Web directory on a server, that information is available for other Web users to view.

URLs and Links 
Every page on the Web has a unique address called a URL, which is short for Uniform Resource Locator. A URL looks like this: http://www.example.com/index.html. If you know a page’s URL, you can type it into a Web browser to view that page over the Internet. You can also view pages by way of hyperlinks, or simply links, which are click-able words or images on Web pages. Every link on a Web page is associated with a URL that leads to another page on the Internet. Users can jump from one Web page to another by clicking links.

Browsers 
A Web browser is software that allows you to view and interact with Web pages. When you type a URL or click a link in a Web browser, the browser retrieves the appropriate page from a server on the Internet and displays that page. Microsoft Internet Explorer, Mozilla Firefox, and Apple Safari are the three most popular browsers in use today. Each program has evolved through a number of versions, with newer versions supporting more recent Web features. As you build your pages using HTML code, remember that different browsers may display your pages slightly differently depending on the version.

WHAT PIECES ARE FOUND IN A COMPUTER?

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Monitor	The CRT or display that shows the words, graphics, etc., to the user. It is a critical part of a user’s interface.
Motherboard	A printed circuit board that has (at least) slots to connect cards into. Often, they also include a CPU and memory.
Mouse	An input device which has one to three buttons and when you move it, it causes the arrow in a Windows display to move.
Printer	An external device that takes commands and data from the computer to place on paper. There are several types of printers: daisy-wheel, matrix, laser, thermal, inkjet, and plotter.
RAM	“Random Access Memory“. A pool of storage for the CPU. It can be written to/read from in any order (unlike a VCR tape which is serial— you have to wind to the place you want). There are several types of RAM: SRAM, DRAM, EDO-RAM.
ROM	“Read Only Memory“. Memory that has imprinted in it data and programs for the CPU which cannot be erased or written to.
Scanner	An external device that is able to optically read in printed material—kind of like a copier, but it stores the image on the computer instead.
UPS	“Uninterruptable Power Supply”. This is a box that is like a surge protector but will keep you going even if you lose power. You can plug your computer into. If you have a brown- or black-out, this unit will keep you running for 3 minutes to an hour (certainly enough time to save your work and shutdown the computer).
CD-ROM	A disk made of plastic and aluminum which can store up to 650MB of data. Usually these disks cannot be written to, instead they often are used to distribute software from companies.
CPU	Central Processing Unit. The “brain” of the computer. It executes commands which, eventually, we see as a response to our input. Without the CPU, the computer is nothing.
Hard disk	A medium to store data for the computer while the power is out. It uses a hard material (typically aluminum).
Keyboard	A typewriter-like tool that has keys. Sends letters or commands to the computer.
Microprocessor	A CPU that composes only one chip. Some CPUs may actually be several square feet is size; but, the microprocessor is designed to be 100% self-contained in a single chip.
Modem	A device that will let your computer talk to other computers through the telephone line.
DVD	The next generation CD-ROM which will store 10-20x the current capacity.
Card Slot	The slots found on the PC motherboard may be one of five types: ISA EISA, MCA, VESA & PCI.. Slower adapters (like I/O boards) can be ISA. But for the best performance, use VESA or PCI for hard drives, CD-ROMs or Video adapters.
Cable Cache	A thick wire that connects the computer to the external device or power. An interface between the CPU and the memory (RAM and ROM). It helps the CPU keep running even though the RAM may be too slow. It does this by keeping a copy of what the processor has read/written.
Adapter	Most of the time it refers to a card that plugs into the motherboard adding special capabilities not originally found on the computer. Other times it refers to tools to convert one connector type to another.

What are Output Devices Of Computer?

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Output Devices: Output Devices of computer are those devices which are used to communicate the computer for displaying process data to the user which is operating the computer. These days many devices are used as output devices of a computer. Most of the computer users only aware of Monitor and Printer as output devices of computer. There are also other output devices which we are using as output devices of a computer. Below are the list of computer output devices.

Output Devices Of Computer

An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world.

In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world. Inputs are the signals or data sent to the system, and outputs are the signals or data sent by the system to the outside.

Examples of output devices:

Headphone - Output Device

• Speakers
• Headphones
• Screen (Monitor)
• Printer

Some more images of Output Devices :

Monitor - Output Device

Printer - Output Device

Speakers - Output Device

What Are Input Devices Of Computer?

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In the world of computing, input devices are any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance. Input and output devices make up the hardware interface between a computer and a scanner. Normally, Input devices of computers are used to give instructions to the computer and output has to be processed through processing devices to output devices. Keyboard and mouse are two famous input devices of a computer which is used in every computer. These days we are also using some latest input devices like Light Pen, Trackball Mouse, and pen drives. Below are some images of input devices of computer:

Keyboard - Input Device

Mouse - Input Device

Scanner - Input Device

Input Devices - Keyboard And Mouse

USB/Pen Drive - Input Device

Many input devices can be classified according to:

• modality of input (e.g. mechanical motion, audio, visual, etc.)
• the input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous)
• the number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)

Pointing devices, which are input devices used to specify a position in space, can further be classified according to:

• Whether the input is direct or indirect. With direct input, the input space coincides with the display space, i.e. pointing is done in the space where visual feedback or the pointer appears. Touchscreens and light pens involve direct input. Examples involving indirect input include the mouse and trackball.
• Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be lifted and repositioned)

Mouse - Input Device

Direct input is almost necessarily absolute, but indirect input may be either absolute or relative. For example, digitizing graphics tablets that do not have an embedded screen involve indirect input and sense absolute positions and are often run in an absolute input mode, but they may also be set up to simulate a relative input mode where the stylus or puck can be lifted and repositioned.

Read detailed article about Input Devices here : http://www.indiastudychannel.com/resources/115991-INPUT-DEVICES.aspx

What is HTML?

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HTML is a language for describing web pages.

• HTML stands for Hyper Text Markup Language
• HTML is not a programming language, it is a markup language
• A markup language is a set of markup tags
• HTML uses markup tags to describe web pages 

HTML Tags

HTML markup tags are usually called HTML tags

• HTML tags are keywords surrounded by angle brackets like <html>
• HTML tags normally come in pairs like <b> and </b>
• The first tag in a pair is the start tag, the second tag is the end tag
• Start and end tags are also called opening tags and closing tags

HTML Documents = Web Pages

• HTML documents describe web pages
• HTML documents contain HTML tags and plain text
• HTML documents are also called web pages

Know more about HTML Tags : http://www.indiastudychannel.com/resources/145204-How-use-HTML-tags.aspx 

What is SQL DML and DDL?

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SQL can be divided into two parts: The Data Manipulation Language (DML) and the Data Definition Language (DDL).

The query and update commands form the DML part of SQL:

• SELECT - extracts data from a database
• UPDATE - updates data in a database
• DELETE - deletes data from a database
• INSERT INTO - inserts new data into a database

The DDL part of SQL permits database tables to be created or deleted. It also defines indexes (keys), specify links between tables, and impose constraints between tables. The most important DDL statements in SQL are:

• CREATE DATABASE - creates a new database
• ALTER DATABASE - modifies a database
• CREATE TABLE - creates a new table
• ALTER TABLE - modifies a table
• DROP TABLE - deletes a table
• CREATE INDEX - creates an index (search key)
• DROP INDEX - deletes an index 

What is SQL?

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• SQL stands for Structured Query Language
• SQL lets you access and manipulate databases
• SQL is an ANSI (American National Standards Institute) standard

What Can SQL do?

• SQL can execute queries against a database
• SQL can retrieve data from a database
• SQL can insert records in a database
• SQL can update records in a database
• SQL can delete records from a database
• SQL can create new databases
• SQL can create new tables in a database
• SQL can create stored procedures in a database
• SQL can create views in a database
• SQL can set permissions on tables, procedures, and views