In the basic 4-way handshake used in secure 802.

They are used to pad Message 1 and Message 2 so each frame contains the same number of bytes.

The IEEE 802.11 standard requires that all encrypted frames contain a nonce to serve as a Message Integrity Check (MIC).

They are added together and used as the GMK, from which the GTK is derived.

They are input values used in the derivation of the Pairwise Transient Key.

They allow the participating STAs to create dynamic keys while avoiding sending unicast encryption keys across the wireless medium.