The IEEE's 802.11g standard is a higher-bandwidth successor to the popular 802.11b, or Wi-Fi standard. 802.11g operates at a maximum speed of 54Mbps whereas 802.11b has a maximum speed of 11Mbps (Megabits/sec). An 802.11g access point compatible with both 802.11b and 802.11g clients. As a result, a laptop computer with an 802.11g card will be able to access existing 802.11b access points as well as new 802.11g access points.
The following are the main advantages of 802.11g over 802.11b:
Higher bandwidth at 54 Mbps.
Cheaper than 802.11a, and costs close to 802.11b. 802.11g uses 2.4GHz frequency band, just like 802.11b.
Backward compatible with 802.11b standard
The main disadvantages are:
Higher cost compared to 802.11b (at least by 50%)
Not yet widely supported by the client machines such as laptops, and PDAs.
Consider the availability of dual band devices while making any procurements. Devices compatible with both 802.11a and 802.11g (inherently compatible with 802.11b) are a good buy considering future expansion and compatibility in diverse network environments.