2.4GHz frequency range is called the ISM (Industrial, Scientific and Medical) band. The ISM band has been set aside by regulatory agencies for unlicensed use by a variety of products including wireless networks using 802.11b and 802.11g WLAN products.
802.11a WLAN products operate in the 5GHz frequency range. This frequency is called the UNII (Unlicensed National Information Infrastructure) band. Like the 2.4GHz ISM band used by 802.11b and 802.11g products, this range has been set aside by regulatory agencies for unlicensed use by a variety of products.
A major difference between the 2.4GHz and 5GHz bands is that fewer consumer products operate in the 5GHz band. This reduces the chances of problems due to radio frequency interference.
This applies to: