Wi-Fi (Wireless Fidelity) is the popular name of RLAN systems that make use of the IEEE 802.11 family of standards.
Officially, it is the name of the certificate which is given by the Wi-Fi Alliance to IEEE 802.11 products which pass their interoperability test. The interoperability of products from different suppliers is tested to make sure that the products of these suppliers can work together in a wireless LAN (RLAN). If a product passes the test, it is allowed to carry the Wi-Fi logo.
The original Wi-Fi certification program covered only IEEE 802.11b products. The certification program is extended to include products based on other IEEE 802.11 family members as well.