TCP/IP

Remember How Computers Talk to Each other? The language that computers use to “talk” to each other over the Internet is TCP/IP.

As we just mentioned, IP addresses help define computers on your LAN. TCP is the communication method in which messages between computers are delivered over the Internet.

TCP/IP is a set of rules that work at the Transport/Network Layer of the 7 Layer OSI Model and is a part of your computer’s system to help connect it for communication over a network – like the Internet.

Picture the Internet as a huge grid. Each opening in the grid is a method of entry to the Internet. This is usually called a “port”. When you perform a certain task (such as e-mailing someone), you use a specific port to help you carry out your task.

Some other ports that are assigned to different applications are:

80: HTTP- Web Browser
21: FTP- File Transfer Protocol
110: POP3- Emailing
25: SMTP- Emailing
443: HTTPS- Secure Web Browsing

Here is a simple analogy to help you better understand TCP/IP. Your company mailbox helps organize mail traffic just like TCP/IP helps to direct specific types of traffic through the Internet. In a company, any incoming mail addressed to a particular employee must arrive at the correct mail slot in order to be delivered to the appropriate person in the company. For example, Ms. HTTP will have a ‘mailbox slot’ (a.k.a. port), Mr. FTP will have a designated ‘mailbox slot’. Each mailbox slot represents a particular application or port in TCP/IP.

The mailbox analogy:

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