The Wi-Fi standard--short for wireless fidelity--is based on the 802.11 specification and is currently the most common standard for wireless home and small-office networking. With an indoor range of about 150 feet and an outdoor range of about 300 feet, Wi-Fi is ideal for small-business hot spots or home wireless LANs. In the simplest networks, a cable or DSL signal is brought into the home via a modem, and a router/access point distributes the signal. Clients, such as laptops and desktop computers, easily latch onto the network via a network adapter. A downside of that ease is that it's just as easy for an interloper to latch onto your Wi-Fi network. Fortunately, the Wi-Fi spec also provides protocols to secure and safeguard your wireless network. WEP, or Wired Equivalent Privacy, was the first such safeguard, though it is widely known that WEP protection is easily hacked. Better yet, use WPA (Wi-Fi Protected Access) or WPA2 security on your network. There are four common flavors of 802.11, each with its own advantages and disadvantages.

802.11n
The 802.11n specification is the most recent development in the realm of Wi-Fi. Although the specification is still being hammered out by the IEEE (and likely won't be finalized until mid-to-late 2006), it is accepted that its technical underpinning will be some version of MIMO (multiple input multiple output), though exactly how MIMO is implemented into the spec remains to be seen. Multiple data paths have generally been the bane of wireless networking--they conflict and interfere with each other, degrading the signal--but MIMO allows developers to take advantage of the multiple data paths to produce stronger signals that travel farther, resulting in faster data throughput, increased range (potentially double that of current 802.11g gear), and greater resistance to the interference rampant in the 2.4GHz spectrum. The lack of specification hasn't stopped networking vendors from creating so-called pre-N MIMO-based products, using proprietary implementations. While the pre-N networking products do show huge gains in throughput and range, they are considerably more expensive than current 802.11g products. And the current lack of specification means that products from different vendors are not guaranteed to interoperate, nor are they guaranteed to work with products based on the final spec. 802.11g
The 802.11g specification is the most recent of the Wi-Fi specs to be approved and is currently the most commonly implemented Wi-Fi standard. Like 802.11n and 802.11b, 802.11g operates in the 2.4GHz spectrum, but without the MIMO advantage of 802.11n, 802.11g is highly subject to interference from other electronic devices that operate in the same spectrum, such as cordless phones and baby monitors. With data transfer speeds of up to 54Mbps (real-world performance is around 22Mbps) and a range of about 150 feet indoors, 802.11g is sufficient for most home and small-office networks and is backward compatible with 802.11b. Additionally, 802.11g allows for broad Wi-Fi hot-spot access. Current 802.11g equipment is relatively inexpensive, making it an ideal choice for most home networks. 802.11b
As the first popular Wi-Fi technology, the 802.11b specification offers slower data speeds than 802.11n, 802.11g, or 802.11a, with a theoretical throughput of 11Mbps and real-world performance of about 5Mbps. Otherwise, its specs mirror those of 802.11g. 802.11b has an indoor range of about 150 feet, and it operates in the 2.4GHz band, making it highly susceptible to interference from other devices. On the positive side, 802.11b products are very inexpensive, if you can find them. 802.11a
The odd duck of the Wi-Fi specs is 802.11a--it's less common but does have certain advantages over 802.11g. 802.11a operates in the 5GHz frequency, which means it's less susceptible to interference from cordless phones and microwave ovens. 802.11a also boasts speeds on a par with 802.11g, though because 802.11g and 802.11a use different frequencies, they can't talk directly to one another. If you're using an 802.11a adapter on a notebook, you won't be able to connect to most Wi-Fi hot spots. 802.11a also lacks the range of the other Wi-Fi flavors, spanning only about 100 feet. Finally, the 5GHz radio inside 802.11a products will drain power faster than a 2.4GHz radio. Dual-band
Dual-band products are a best-of-all-worlds solution: they are compatible with all the current 802.11 standards. The 802.11a/b/g gear operates at 2.4GHz and 5GHz, so dual-band networking gear is more resistant to interference. The big downside? Price. For all the benefits, you'll pay mightily, often double what you'd pay for single band products.