Wardriving is a wireless networking term that refers to the event when a person in a moving vehicle with a Wi-Fi equipped computer like a laptop or a personal digital assistant (PDA) roams around a given location to search for Wi-Fi wireless networks. This instance is comparable to the use of a radio scanner, or to DXing (distancing), which is when HAM radio operators tune in and identify distant radio signals or make two-way radio contact with distant stations.

"Wardriving" has been derived from the term "wardialing," which comes from the 1983 movie, WarGames. Wardialing was the practice of using software that dialed numbers sequentially in order to see which numbers were connected to a fax machine or computer, in order to locate computer systems.

There is a variety of software for wardriving which is available for free download on the internet. This includes the following: NetStumbler for Windows; Net Berkeley Software Distribution (NetBSD), OpenBSD, FreeBSD, and DragonFly BSD, and KisMAC for Macintosh; and Kismet or SWScanner for Linux. The software may be categorized into the two types of wardriving, passive and active. Kismet and KisMAC are used for passive wardriving, which only logs in the broadcast address of a network without actually communicating with it. NetStumbler is used for active wardriving, which actively sends probe messages and waits for the access point to respond.

Wardriving has spawned a number of derivations of the term, such as warbiking and warwalking. Both activities are similar to wardriving, only differing in the mode of transportation. In warbiking, the person travels on a moving bicycle or motorcycle with a Wi-Fi capable device mounted on it. In warwalking, the person travels on foot, bringing a handheld Wi-Fi capable device such as a Pocket PC. This practice usually leads to the discovery of fewer networks due to the slower speed of travel.

Global Positioning System (GPS) devices are often used by wardrivers in order to determine the exact location of the network and log it on to a website, such as WiGLE.net, with the purpose of forming maps of the network neighborhood. Antennas, from omni directional to highly directional, are built or bought in order to achieve better range for GPS devices.

The practice of wardriving faces a number of legal and ethical considerations. It is often associated with the illegal practice of piggybacking, which is bringing a personal computer to the area of someone else’s wireless connection and using its services without proper authorization or knowledge of the subscriber, although wardriving is different in that wardrivers only collect information on wireless networks without using the networks’ services.

Access points have to broadcast identifying data which is accessible to anyone equipped with a suitable receiver, so from a technical viewpoint, everything is working as designed, and wardriving is merely a practice comparable to mapmaking. There are currently no laws passed on the prohibition of wardriving; however, a number of localities do have laws prohibiting unauthorized access of a computer network.