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3. Application Layer
Layer 4. Application Layer
The layer of protocols dealing with user applications and how data moves in and out of these applications.
The Application Layer is the topmost layer in the Four Layer Model.
The protocols in this layer govern how data moves in and out of applications. It is where the network applications such as web browsers or email programs operate.
If you have already read the section on protocols then you will know that:
- Web browsers use the HTTP & HTTPS protocols
- Email applications use the POP and SMTP protocols
- Servers use the FTP protocol
As mentioned earlier, layers can only 'talk' to adjacent layers. That is, the protocols in the Application layer only interact with the protocols in the Transport layer.
| Layer | Layer Name |
|---|---|
| 4 | APPLICATION |
| 3 | TRANSPORT |
| 2 | NETWORK or INTERNET |
| 1 | DATA LINK or NETWORK INTERFACE |
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: What is the Application Layer?