In a free-form network, stations must create an explicit association with one another before they can exchange unicast data traffic. In a medium where reception can be problematic, each unicast data packet is separately acknowledged. Because stations cannot detect collisions created by their own transmissions, special rules are needed to control access to the airwaves.

The public nature of radio transmissions and the desired flexibility of network membership create special challenges for security, requiring special authentication and confidentiality measures.

WLAN Physical-Layer Standards
The first 802.11 standard was published by the Institute of Electrical and Electronics Engineers (IEEE) in 1997. Since that original standard, many amendments and corrections have been published, and versions of the standard (and amendments) have been adopted as standards by the ISO.

It is conventional to refer to various aspects of the standard by the name of the revision document in which they were first introduced—for example: 802.11b, 802.11i, and so forth. We follow this convention when distinguishing between physical medium specifications (802.11a, b, g, and n). It is important to recognize, however, that all of these documents form a single integrated set of specifications for wireless networks, some parts of which are optional and others mandatory.