The practice of using chalk markings on sidewalks or buildings to alert other geeks to the presence of a wireless IEEE 802.11-compatible network capable of providing Internet access.

Invented in London by Matt Jones, and chronicled at his website,, this system was inspired by a similar chalking system used by hobos during the Great Depression to communicate to others where food and shelter could be found.

In the current system, three basic markings are used to signify whether the network is open, closed, or secured using Wireless Equivalent Privacy. Additional parameters such as the access point's password and bandwidth can be inscribed as well.