To provide access to the Internet or to servers, printers, and other resources on a wired LAN, a wireless LAN (WLAN) must operate in _infrastructure_ mode. This requires at least one _access point_ (AP), a wireless device that connects to the wired LAN and acts as a bridge between the wired and wireless portions of the network.

To join an infrastructure WLAN, a wireless station must be configured for infrastructure mode, given the same SSID as the AP, and given suitable security settings. Assuming the AP broadcasts its SSID and does not use encryption; stations can configure themselves and "associate" with the AP completely automatically. Stations on an infrastructure WLAN are often referred to as "wireless clients." All their communications, whether with the wired LAN or with each other, go through the AP.

By placing multiple APs on a wired LAN and giving them the same SSID and suitable security and channel settings, a WLAN with a very large coverage area can be created. Because APs' coverage areas will overlap in some places, the APs must be set to use non-overlapping transmission channels. Stations automatically use the channel of the AP with the strongest signal; this allows them to "roam" throughout the WLAN.

("Suitable security settings" usually means security settings identical to those of the other devices on the WLAN. When using multiple 64-bit WEP keys, however, it is not necessary to select the same key as the transmit key, often called the "default key," on all devices. Standards-compliant devices can decrypt transmissions sent using any one of the authorized keys, as long as the keys are entered and numbered identically.)

To allow wireless communication where an access point is not available or access to a wired network is not required, IEEE 802.11 provides ad hoc mode. Stations on an ad hoc WLAN communicate directly with each other.

To join an ad hoc WLAN, a wireless station must be configured for ad hoc mode, given the same SSID as all the other stations, given suitable security settings, and set to use the same channel as all the other stations.

Typically, wireless stations will not connect automatically to an ad hoc WLAN. Once one station is configured, however, assuming it broadcasts its SSID and does not use encryption; other users can join with one or two clicks in their wireless configuration software's "site survey" or "available networks" display.