OSI Model

Application Layer

Provides network services directly to end users and applications (e.g., web browsers, email clients). Defines how applications interact with the network.

HTTP, HTTPS, FTP, SMTP, DNS, POP3

Presentation Layer

Translates data between the application and network formats. Handles data encryption, compression, and conversion (e.g., from ASCII to binary).

SSL/TLS, JPEG, MPEG, ASCII

Session Layer

Manages sessions or connections between applications. Establishes, maintains, and terminates sessions.

NetBIOS, RPC, PPTP

Transport Layer

Ensures reliable data transfer between devices. Handles error detection, correction, and flow control.

TCP, UDP

Network Layer

Determines how data is sent between networks (routing). Uses logical addressing (IP addresses).

IP, ICMP, IPsec, Routers

Data Link Layer

Provides reliable node-to-node data transfer. Uses physical (MAC) addresses and handles error detection at the frame level.

Ethernet, PPP, Switches, MAC addresses

Physical Layer

Transmits raw bitstreams over a physical medium. Defines cables, connectors, and signalling methods.

Hubs, Cables, NICs, Wi-Fi, Bluetooth