Internet Protocol Stack

• The closer to this bullet, the higher level it is.
• Application. FTP, SMTP, HTTP. Handles Messages. SSL belongs here
• Presentation. Encryption, Compression. Machine specific.
• Session. Synchronization, Checkpointing, Recovery.
• Transport. TCP. UDP. TCP vs UDP. Handles Segments.
• Network. IP. Routing Protocols. Handles Datagrams.
• Link. Ethernet, Wi-Fi, Point-to-Point Protocol (PPP). Handles Frames.
• Physical. Wire.
• The closer to this bullet, the lower level it is.

Note that a TCP message is not a packet because it is a byte stream.