OSI model (also known as ISO/OSI)

TLDR

The OSI model is a set of 7 layers that standardize the communication process between different network devices. The layers are:

1. Physical - Responsible for transmission of raw data, examples: Network Switch, Ethernet Hub, NIC card.
2. Data Link - Provides a link and data transfer between two nodes, managing the connrection between devices, it also detects/prevents errors that originate from the physical layer.
3. Network - Provides a mean for nodes to transfer data - packets, between each other, with each node having its own address.
4. Transport - Allows the transfer of variable-length data, from a host to their destination. Large amounts of data may require breaking it up into segments.
5. Session - Controls the connection between two, or more nodes.
6. Presentation - Handles formatting, de/encryption, de/compression, and encapsulation of data.
7. Application - Provides a means for end-users to interact with the network, it uses protocols such as HTTP, FTP, or SMTP.

Physical layer

Data Link layer

Network layer

Transport layer

Session layer

Presentation layer

Application layer