an Internet service

introduction

There are many Internet services. The Internet is defined as a series of layers, with each layer providing many services to the layers above.

1. Application Layer
2. Transport Layer
3. Internet Layer
4. Link Layer

Most services are used to make the Internet work behind the scenes, and are only interesting to Internet technicians. When most people think about Internet services, they are thinking about one of the services that runs in the application layer - the web service.

Internet service layers

The Internet works because many communications protocols were created and brought together to form the Internet Protocol Suite. The design is split into four layers. Dozens of protocols define how each layer works.

Designing the Internet using a series of layers simplifies communication. An application working in one layer does not have to know the details of how the other layers work. Layers make it easier to provide alternatives to creaky old protocols, such as adding IPv6 to the Internet layer, alongside IPv4.

The only Internet services most people see are at the application layer. This is where services to customers live.

the application layer

People using Internet services are relying on applications talking Internet protocols. People have been copying files across the Internet using FTP protocol for decades. Thousands of programmers have created thousands of applications that talk FTP.

The part in capitals is the name of the protocol. The service name is in brackets.

1. DNS (name resolution)
2. FTP (file copy)
3. HTTP (web)
4. IRC (chat)
5. NNTP (news)
6. NTP (time)
7. POP (message receipt)
8. SMTP (message send)
9. SSH (secure communication)
10. SSL (secure web)

By far the most well known is HTTP, used to provide web services. The most common type of outsourced hosting is shared web hosting, a cheap and cheerful product designed for web services.