The OSI (Open Systems Interconnection) Model is a framework that subdivides networking functions into seven separate layers. Each of the layers cover a distinct range of network functions, each of which work together to make networking and networking between differing software and hardware possible. Generally speaking, the bottom 2-3 layers deal mostly with hardware and the top 4-5 deal predominately with software. The OSI stack is detailed in the table below:

Layer	Protocol/Hardware examples	Short Description
7.Application	FTP, Telnet, SMTP	Provides network access and network resources for applications.
6.Presentation		Data Presentation, Encryption and Compression. Prepares data for use by Application layer.
5.Session	NFS, SQL	Establishes, Monitors and Terminates Sessions.
4.Transport	TCP, SPX	Name Resolution. Segmentaion. Reliable transport. Establishing end-to-end connections - handshaking.
3.Network	Routers, IP, IPX, RIP, OSPF	Routing - Route Discovery and Route Determination. Software, Logical or Network Addressing. Packet reassembly.
2.Data Link	Bridges, Switches, Ethernet, FDDI	Only layer that is subdivided into two sub-layers. MAC (Media Access Control) and LLC (Logical Link Control). Hardware addressing. Logical topologies. Media Access.
1.Physical	Cabling, Hubs, RS-232, v.90	Signalling, Media and media specifications, Physical connections, Physical topologies.