What are the seven layers of the OSI model?

The Open Systems Interconnection model has seven layers from bottom to top: physical layer one handles electrical signals and cables, data link layer two handles MAC addresses and switches, network layer three handles IP addresses and routing, transport layer four handles TCP and UDP port-based communication, session layer five manages connections between applications, presentation layer six handles data formatting and encryption, and application layer seven interfaces with user applications. The mnemonic "Please Do Not Throw Sausage Pizza Away" helps remember the order.