WLAN (Wireless Local Area Network) enables users to connect to a LAN through a wireless connection. It uses high-frequency radio waves instead of wires at the physical layer. With such benefits as network flexibility and end user mobility, WLAN has become increasingly popular in home networks, hot spots like cafes, hotels, and airports, educational campuses, as well as enterprise networks.

The term 802.11 (commonly interchangeable with WLAN) refers to a family of specifications from the IEEE (Institute of Electrics and Electronics Engineers) for wireless LAN technology. The initial 802.11 specification was ratified in 1997. There are three key flavors of 802.11 WLAN technology: 802.11a, 802.11b, and 802.11g.

802.11b operates in the unregulated 2.4 GHz range and supports data rates up to 11 Mbps. It was certified by the IEEE in 1999 and is the basis for WECA's (Wireless Ethernet Compatibility Alliance) Wi-Fi certification ensuring interoperability. It uses spread spectrum technology. Because of its low price and early entrance on the market, 802.11b is the most common version found in home and hot spot networks.

- 802.11b Pros: lowest price; best signal range
- 802.11b Cons: subject to interference from other appliances using the same frequency, including cordless phones, Bluetooth devices, and microwave ovens; slowest speed; supports fewest number of users

802.11g is considered the successor of 802.11b and has been available since 2002. It too operates in the 2.4 GHz range, but can support bandwidths up to 54 Gbps. It uses Orthogonal Frequency Division Multiplexing (OFDM) technology. 802.11g is backwards compatible with 802.11b meaning that 802.11b cards will work with 802.11g access points and vice versa.

- 802.11g Pros: fastest speed; best signal range; supports more users than 802.11b
- 802.11g Cons: subject to interference from other appliances using the same frequency

802.11a operates in the 5 GHz frequency range and supports data speeds up to 54 Mbps. Like 802.11g, it uses Orthogonal Frequency Division Multiplexing (OFDM) technology. It supports twelve non-overlapping channels, so one can configure twelve access points in the same area without interference. The 5 GHz range is less crowded with interfering devices than the 2.4 GHz range. Due to its higher cost, 802.11a is better-suited for the corporate market, whereas 802.11b fits the home user. - 802.11a Pros: fastest speed; subject to less interference in the 5 GHz range; supports more users than 802.11b
- 802.11a Cons: higher frequency limits the signal's range; highest cost

Wireless LANs can be configured in two modes: ad hoc or infrastructure. In ad hoc networking, also known as peer-to-peer, computers (or end devices) communicate with one another. All wireless nodes serve as equal peers and form an Independent Basic Service Set (IBSS). These connections can take place anywhere and are convenient for temporary connections, like in meetings. In infrastructure networking, computers (or other wireless end devices) communicate with an Access Point (AP) that connects to the wired LAN. It is the AP that enables the wireless devices to access the wired network.

Security issues surrounding WLAN have been the greatest hurdles to its adoption in the corporate network. In the past 2 years, significant improvements have been made to improve WLAN's security through the IEEE's 802.11i standard and the WIFI Alliance's WPA/WPAs (Wifi-Protected Access) certificates. A properly engineered security system can provide robust security. It requires a multi-layered approach that includes user authentication, data encryption over the wireless link, policy management to control access, and lastly, monitoring and auditing systems.

WLANs can either replace or extend a traditional wired LAN. They can increase the flexibility of the network since it's easy to add or relocate workstations without having to run cable. This is a key advantage for:

- Temporary networks, like at construction sites and tradeshows
- Growing businesses where there is frequent office rearrangement
- Old buildings that are difficult to wire

WLAN enables employees to stay connected as they move throughout the corporate campus- giving them continuous access to the network and email. This is crucial for highly-mobile employees like warehouse or medical staff. Teams can create temporary ad-hoc networks to better collaborate on projects.

An emerging application is Voice over IP over WLAN. This allows mobile staff, including retail employees, security guards, hotel staff, and hospital workers to be in constant communication while moving about the facility.