# 802.11 Frame Structure

The meat and potatoes of WiFi. Essentially everything transmitted by a wireless NIC comes in the form of a frame. They are the basic unit of most digital transmissions, and surround or encapsulate packets.

### Frame Structure

A typical WiFi frame is broken up into several sections, consisting of a MAC header, payload and frame check sequence

**The MAC header** contains a Frame Control Field which includes, among other things, the 802.11 protocol version and frame type. Address fields including the BSSID, source and destination are also part of this section.

**The Payload** or frame body contains the actual information (typically a data packet) of either a management or data frame.

**The Frame Check Sequence** (FCS) concludes the frame with a cyclic redundancy check (CRC) sum of the MAC header and payload. This is used to verify the integrity of the frame and is essential to fault tolerance.