IEEE 802.11 in the context of Medium access control

Wi-Fi (/ˈwaɪfaɪ/) is a family of wireless network protocols based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves. These are the most widely used computer networks, used globally in home and small office networks to link devices and to provide Internet access with wireless routers and wireless access points in public places such as coffee shops, restaurants, hotels, libraries, and airports.

Wi-Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term "Wi-Fi Certified" to products that successfully complete interoperability certification testing. Non-compliant hardware is simply referred to as WLAN, and it may or may not work with "Wi-Fi Certified" devices. As of 2017, the Wi-Fi Alliance consisted of more than 800 companies from around the world. As of 2019, over 3.05 billion Wi-Fi-enabled devices are shipped globally each year.

Wireless speakers are loudspeakers that receive audio signals using radio frequency (RF) waves rather than over audio cables. The two most popular RF frequencies that support audio transmission to wireless loudspeakers include a variation of WiFi IEEE 802.11, while others depend on Bluetooth to transmit audio data to the receiving speaker.

Apart from the employed RF standard, such speakers can basically be distinguished by their dedicated field of use. Portable wireless speakers for outdoor use are typically designed for ruggedness, portability and battery life, whereas stationary wireless speakers with a focus on good sound quality are meant to be used in home audio systems or surround sound systems for TV or video. Further, types for special applications like waterproof speakers for use in the shower or speakers for a voice assistant may intermix between the properties of the two former.

The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, particularly satellites used by NASA to communicate with the Space Shuttle and the International Space Station. The 10 cm radar short-band ranges roughly from 1.55 to 5.2 GHz. India's regional satellite navigation network (IRNSS) broadcasts on 2.483778 to 2.500278 GHz.

The S band also contains the 2.4–2.483 GHz ISM band, widely used for low power unlicensed microwave devices such as cordless phones, wireless headphones (Bluetooth), garage door openers, keyless vehicle locks, baby monitors as well as for medical diathermy machines and microwave ovens (typically at 2.495 GHz). One of its largest uses is 2.4 GHz IEEE 802.11 Wi-Fi wireless networks, allowing smartphones, laptops, printers and TVs to connect to the internet without cables.

The C band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 4.0 to 8.0 gigahertz (GHz). However, the U.S. Federal Communications Commission C band proceeding and auction, designated 3.7–4.2 GHz as C band. The C band is used for many satellite communications transmissions, some cordless telephones, as well as some radar and weather radar systems.

The C band contains the 5.725 - 5.875 GHz ISM band allowing unlicensed use by low power devices, such as garage door openers, wireless doorbells, and baby monitors. A very large use is by the high frequency (5.2 GHz) band of Wi-Fi (IEEE 802.11a) wireless computer networks. These are the most widely used computer networks in the world, used to allow laptops, smartphones, printers and TVs to connect to the internet through a wireless router in home and small office networks, and access points in hotels, libraries, and coffee shops.

A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. This gives users the ability to move around within the area and remain connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet.

Wireless LANs based on the IEEE 802.11 standards are the most widely used computer networks in the world. These are commonly called Wi-Fi, which is a trademark belonging to the Wi-Fi Alliance. They are used for home and small office networks that link together laptop computers, printers, smartphones, Web TVs and gaming devices through a wireless network router, which in turn may link them to the Internet. Hotspots provided by routers at restaurants, coffee shops, hotels, libraries, and airports allow consumers to access the internet with portable wireless devices.

A radio access technology (RAT) is the underlying physical connection method for a radio communication network. Many modern mobile phones support several RATs in one device such as Bluetooth, Wi-Fi, and GSM, UMTS, LTE or 5G NR.

The term RAT was traditionally used in mobile communication network interoperability.More recently, the term RAT is used in discussions of heterogeneous wireless networks. The term is used when a user device selects between the type of RAT being used to connect to the Internet. This is often performed similar to access point selection in IEEE 802.11 (Wi-Fi) based networks.