Before ordinary Wi-Fi data exchange, a station chooses and associates with an access point in a wireless network.

Access points advertise network information, while stations discover candidates by listening or actively probing. Authentication and association establish the link-layer relationship needed to exchange frames through the chosen access point; higher-layer configuration such as DHCP can follow afterward.

A device moving through a building may discover another access point belonging to the same logical network. Roaming changes the station's link-layer attachment. Whether applications notice depends on what else changes: preserving IP connectivity can allow transport sessions to continue, while changing subnets or address translation state can disrupt them.

Roaming therefore exposes the distinction between layers: changing the local radio attachment is a link-layer event, but its user-visible effect depends on network and transport state above it.