MARKUP LANGUAGE

Marup language are designed to create an appropriate markup scheme for an electronic document or web page. The language specifies the code for formatting, both the layout and style, within a text file. HTML is an example of markup language. We will learn the details of HTML in unit - II.

PROTOCOLS

We live in a world where millions of people speak hundreds of different languages. We would have never been able to communicate worldwide if there were no 'standards' governing the way we communicate, and the way our manchines process data. These standards are nothing but sets of rules, which are followed by everyone.

Similarly, there are specific rules, which determine how the data should be transferred over the networks, compressed, presented on the screen, and so on. These sets of rules are called Protocols.

Likewise, there are many other protocols, each one governing the way a particular technology works. Hence, the basic need for protocols is to standardise the processes and ways of communicating over a computer network. Lets us learn about the most common protocols and their unique features :

TCP / IP

TCP / IP stands for Transmission Control Protocol / Internet Protocol. It is a family of protocols defining conversations for communication between computers over the Internet. It is the basic communication protocol of the Internet.

TCP / IP is a two - layer program. The higher layer, TCP, manages the breaking down and assembling of the data, whereas the lower layer, IP, is responsible for the accurate delivery of the data over the Internet.

For examples, when we access our Gmail account, the process of HTTP transaction takes place as shown below : In the first step, we open a connection to the Gmail server by typing the URL, http://www.gmail.com. This URL actually sends an HTTP command to the web server directing it to fetch and transmit the requested web page. In the second step, we enter our credentials in the form of username and password. When we click on Login, a request is sent to the server starting the type of transaction and the data. The transaction type is Login and the data requested is your e - mail account. In the third stage, the server checks whether the username and password are entered correctly or not. If the credentials are correct, the server sends the desired data, hence the current status is 'Success'. If the credentials do not match, the server redirects you to the home page with an error message. The currect status of this transaction becomes 'Failure'.

How does TCP / IP work ?

The information that we send through the Internet is broken into packets by TCP using the technique of Packet - switching . It is a digital networking communication method which breaks the large data into suitably - sized blocks known as Packets. The IP is responsible for sending these packets to the right address by assigning them a sequence number. The packets are sent to a local Internet Service Provider (ISP). From here, the packets travel through multiple levels of networks, computers, and communication lines before reching the destination. This destination may be our town or anywhere across the globe. When the information packets reach the destination computer, the TCP with the help of packet - switching, again assembles the packets into a single message.

HTTP

HTTP or Hypetext Transfer Protocol determines how different programs exchange data over the Internet. The HTTP is the standard protocol used by the World Wide Web. It defines how messages are formatted and transmitted, and what actions the web servers and browsers should take in response to various commands.

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