Wi-Fi™ is a WLAN (Wireless Local Area Network) technology. It primarily provides short-range wireless high-speed data connections between mobile data devices (such as laptops, PDAs or phones) and nearby Wi-Fi access points (special hardware connected to a wired network and the Internet.)
Wi-Fi is generally faster than data technologies (like 4G and 5G) operating over a cellular network.
Wi-Fi is much shorter-range, however. Wi-Fi coverage is only provided in small, specific areas called "hot spots". Other than some large buildings (airports, convention centers) and campuses, Wi-Fi coverage is not widespread. Range for a typical Wi-Fi base station (access point) is typically around 100 to 300 feet indoors and up to 2000 feet outdoors.
Wi-Fi networks can be set up and operated by anyone, with different networks allowing different kinds of access. A public "hot spot" at an airport or coffee shop might charge an hourly rate for access. A hotel might offer free wi-fi to guests. A company or university might offer on-premises free access for verified employees/students. Or a home user could set up their own network to which only they had access.
While most Wi-Fi connections are between a mobile device and an access point, it is also possible to create an "ad-hoc" network directly among two or more devices, without an access point. This is sometimes done using a technology called Wi-Fi Direct.
802.11 is the name of the technical standard for Wi-Fi. A number of updates to 802.11 have been released over the years bringing support for new features and additional frequency bands, offering faster data speeds. Versions of the Wi-Fi standard include, in order of oldest to newest:
- 802.11b: The original standard, offering speeds up to 11 Mbps in the 2.4 GHz band.
- 802.11a: Supports only the less-crowded 5 GHz band and newer OFDM technology, offering speeds up to 54 Mbps.
- 802.11g: Brought OFDM and 54 Mbps speeds to the 2.4 GHz band.
- 802.11n: Replaced all previous standards for both bands. Supports more advanced OFDM and MIMO for much faster speeds (up to 600 Mbps). Also known as Wi-Fi 4.
- 802.11ac: A more advanced, faster (up to 5x) alternative for the 5 GHz band. Also known as Wi-Fi 5.
- 802.11ax: A replacement for 802.11n that operates in both existing bands and offers faster speeds (potentially up to 9.6 Gbps). Also known as Wi-Fi 6. It can also support the new 6 GHz band, in which case it is also known as Wi-Fi 6E.
Most newer devices, supporting newer standards, support the older standards as well, for backward compatibility.
However cheaper devices may only support the 2.4 GHz band, so a device can support 802.11n (in the 2.4 GHz band only) without supporting 802.11a. Devices that support both 2.4 GHz and 5 GHz are "dual-band".
Wi-Fi operates in unlicensed frequency bands, which means anyone can use them without a license from the government. However the rules for these bands limit transmit power, which limits range. And technologies using these bands must try to avoid interfering with other nearby users.
However there is still a limit to how many users can share a band in one location at the same time. More crowded bands become slower and less reliable for everyone.
The 2.4 GHz band is the oldest and therefore most "crowded" band. Bluetooth and other technologies also use the same band, adding to the crowding.
802.11a and 802.11ac operate exclusively in the 5 GHz unlicensed frequency band. 802.11n and 802.11ax can also use this band. Since the 5 GHz band is often not as "crowded" as the 2.4 GHz band, it can be faster in many cases. This is even more true for the newer 6 GHz band available to Wi-Fi 6E devices.
Wi-Fi is a trademark of the Wi-Fi Alliance, a nonprofit industry association. "Wi-Fi" isn't short for anything. The "Wi" part is suggestive of "wireless" and the whole term is suggestive of "hi-fi", but "Wi-Fi" is technically its own trademark and not an acronym, nor an abbreviation.