TCP/IP Protocol

What is TCP/IP?

TCP/IP stands for Transmission Control Protocol / Internet Protocol. It defines how electronic devices (like computers) should be connected over the Internet, and how data should be transmitted between them.
TCP - Transmission Control Protocol
TCP is responsible for breaking data down into small packets before they can be set over a network, and for assembling the packets again when they arrive.
IP - Internet Protocol
IP takes care of the communication between computers. It is responsible for addressing, sending and receiving the data packets over the Internet.

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TCP/IP Protocols For the Web

Web browsers and servers use TCP/IP protocols to connect to the Internet. Common TCP/IP protocols are:
HTTP - Hyper Text Transfer Protocol
HTTP takes care of the communication between a web server and a web browser. HTTP is used for sending requests from a web client (a browser) to a web server, returning web content (web pages) from the server back to the client.
HTTPS - Secure HTTP
HTTPS takes care of secure communication between a web server and a web browser. HTTPS typically handles credit card transactions and other sensitive data.
FTP - File Transfer Protocol
FTP takes care of transmission of files between computers.

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IP is Connection-Less

IP is a "connection-less" communication protocol.
IP does not occupy the communication line between two computers. This reduces the need for network lines. Each line can be used for communication between many different computers at the same time.
With IP, messages (or other data) are broken up into small independent "packets" and sent between computers via the Internet. IP is responsible for "routing" each packet to the correct destination.

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IP Routers

When an IP packet is sent from a computer, it arrives at an IP router.
The IP router is responsible for "routing" the packet to the correct destination, directly or via another router.
The path the packet will follow might be different from other packets of the same communication. The router is responsible for the right addressing, depending on traffic volume, errors in the network, or other parameters.
Analogi: Communicating via IP is like sending a long letter as a large number of small postcards, each finding its own (often different) way to the receiver.

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IP Addresses

IP uses 32 bits, or four numbers between 0 and 255, to address a computer.
IP addresses are normally written as four numbers separated by a period, like this: 192.168.1.50.
Each computer must have an unique IP address before it can connect to the Internet.
Each IP packet must have an address before it can be sent to another computer.
This is an IP address: 192.68.20.50. This might be the same address:  www.w3schools.com
This is your IP address: 108.161.252.139
In computer terms, TCP/IP uses 32 bits addressing. It uses 4 bytes. One byte is 8 bits. One byte can contain 256 different values:
00000000, 00000001, 00000010, 00000011, 00000100, 00000101, 00000110, 00000111, 00001000 .......and all the way up to 11111111.

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Domain Names

A name is much easier to remember than a 12 digit number.
Names used for TCP/IP addresses are called domain names.
w3schools.com is a domain name.
When you address a web site, like http://www.w3schools.com, the name is translated to a number by a Domain Name Server (DNS).
All over the world, DNS servers are connected to the Internet. DNS servers are responsible for translating domain names into TCP/IP addresses.
When a new domain name is registered together with a TCP/IP address, DNS servers all over the world are updated with this information.

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