OSI Learning
OSI

Interactive OSI Model — Learn by clicking

Explore the 7 layers, see protocols & examples, watch encapsulation, and test knowledge with a short quiz.

Layer 7 — Application
User-facing services & apps
HTTP, SMTP, DNS
Layer 6 — Presentation
Data format, encryption, compression
SSL/TLS, MIME
Layer 5 — Session
Connections, sessions, dialogs
RPC, NetBIOS
Layer 4 — Transport
Host-to-host communication, reliability
TCP, UDP
Layer 3 — Network
Routing and addressing
IP, ICMP
Layer 2 — Data Link
Framing, MAC addressing, switches
Ethernet, ARP
Layer 1 — Physical
Cables, bits, physical signals
Ethernet PHY, Fiber
Tip: click any layer to open details, or press Enter when focused.

Click a layer to begin

Start by selecting a layer from the diagram on the left. You'll see: definition, real-world examples, common protocols, and a short interactive demo that illustrates how data travels through that layer.

Packet Travel & Full Encapsulation Demo

Host A
Router
Host B