Tell about the OSI model — what is it?

The OSI (Open Systems Interconnection) model is a reference network model developed to standardize the functions of network protocols and ensure interaction between different systems. It divides the data transmission process into 7 layers:

1. Physical — transmission of bits over a physical channel.
2. Data Link — framing, media access control.
3. Network — routing and logical addressing (e.g., IP).
4. Transport — reliable data transfer, flow control (TCP, UDP).
5. Session — establishing, managing, and terminating communication sessions.
6. Presentation — data transformation, encoding, encryption.
7. Application — interface for applications, high-level protocols (HTTP, FTP).

This model helps understand how data passes through a network and serves as a basis for developing and analyzing network protocols.