What is a protocol?
A protocol is a set of rules. Think of two people talking. They need the same language and the same manners, or they will not understand each other. Computers are the same. A protocol is the shared language that lets them talk.
The most common one: TCP/IP
The answer most people give is TCP/IP. It is really two protocols that work as a team.
- IP stands for Internet Protocol. It gives every device an address, called an IP address. It is like a house number on a street.
- TCP stands for Transmission Control Protocol. It breaks data into small pieces called packets. It sends them and checks that all of them arrive. If one is lost, it sends it again. It is like a courier who gets a signature on every parcel.
Almost everything you do online sits on top of TCP/IP.
Other common protocols
| Protocol | What it does |
|---|---|
| HTTP | Loads web pages |
| HTTPS | The same as HTTP, but locked and private |
| DNS | Turns a domain name into an IP address |
| SMTP | Sends email |
| IMAP and POP3 | Let you read email |
| FTP | Moves files to and from a server |
| UDP | Sends data fast without checking, used in video calls and games |
What happens when you open a website?
- You type a domain name in your browser.
- DNS finds the IP address for that name.
- Your computer opens a TCP connection to the server.
- Your browser asks for the page using HTTPS.
- The server sends the page back in packets.
- Your browser puts the packets together and shows the page.
Which is the most common, then?
For the whole internet, it is TCP/IP. For web browsing, it is HTTP and HTTPS. For hosting, you use all of them every day, even if you do not see them.
Tip: Look at the start of a web address. If it begins with
https://, the connection is protected.Quick recap
- A protocol is a set of rules computers follow to talk.
- TCP/IP is the base of the internet.
- HTTP and HTTPS load websites.
- DNS, SMTP, IMAP and FTP each do one special job.