The 7-Layer OSI Reference Model & Encapsulation

The Open Systems Interconnection (OSI) model standardizes telecommunication functions into seven logical layers. Data transmitted across a network undergoes encapsulation as it travels down the stack:
• Layer 7 (Application): HTTP/HTTPS, DNS, and SSH.
• Layer 4 (Transport): End-to-end communication via TCP and UDP.
• Layer 3 (Network): Logical addressing and routing via IPv4 and IPv6.
• Layers 2 & 1 (Data Link & Physical): MAC frame switching and physical bit transmission.