Wireless technologies have become increasingly popular in the everyday business and personal lives. Personal Digital Assistants (PDAs) allow individuals to access calendars, e-mail, address and phone number lists and the Internet. In this paper, provides details about the research done in the field of 802.11 WLAN technologies. It includes introductory material on the history of 802.11 and provides other technical information, including 802.11frequency ranges and data rates, network topologies, transmission ranges and applications. It examines the security threats and vulnerabilities associated with WLANs and offers various means for reducing risks and securing WLAN environments.