Wi-Fi

Wi-Fi is a family of wireless network protocols that let nearby digital devices, like computers and phones, talk to each other and access the internet using radio waves. It's the most common way we connect devices at home, in offices, and even in public places like coffee shops, libraries, and airports, thanks to wireless routers and wireless access points.

The term "Wi-Fi" is a trademark of the Wi-Fi Alliance, a group of over 800 companies that makes sure devices can work together properly. This means that any device labeled "Wi-Fi Certified" has passed tests to ensure it can connect with other certified devices.

Wi-Fi works with different versions of the IEEE 802.11 standards, each offering various speeds and ranges. It mostly uses radio waves in the 2.4 gigahertz and 5 gigahertz ranges, with newer versions using the 6 gigahertz band too. These signals work best when there's a clear path, so walls and other obstacles can reduce how far they reach. Typically, a Wi-Fi signal can cover about 20 meters indoors, but in open areas, it can stretch much farther.

Over the years, Wi-Fi has become faster and more efficient. By 2025, some advanced versions of Wi-Fi could reach speeds of up to 23 Gbit/s, making it possible to download large files or stream high-quality videos very quickly.

History

Main article: IEEE 802.11 § History

In 1985, the U.S. Federal Communications Commission allowed certain radio frequencies for communication devices, which later helped create Wi-Fi. In 1991, two companies in the Netherlands created an early version of Wi-Fi for cash registers. In 1992, scientists in Australia began working on similar technology.

The first official Wi-Fi standard was released in 1997. By 1999, Apple made Wi-Fi popular by including it in their laptops. Wi-Fi continued to grow and improve over the years, becoming a common way for devices to connect to the internet without wires.

Etymology and terminology

The name Wi-Fi was created in August 1999 by a company called Interbrand. They were hired to make a catchier name than "IEEE 802.11b Direct Sequence." The Wi-Fi Alliance chose Wi-Fi from a list of ten names. Although it sounds like "Wireless Fidelity," that was just an early advertising slogan and not the real meaning. The name was picked partly because it sounds like Hi-Fi, which people associate with high quality.

Wi-Fi is used for connecting devices like computers to the internet without wires. To use Wi-Fi, a computer needs a special part called a wireless network interface controller. Devices using Wi-Fi can talk to each other directly or through a base station. Each Wi-Fi network has a name, called an SSID, that helps devices find and connect to the right network.

logo
yin-yang
interoperability
advertising slogan
IEEE
Hi-Fi
Motorola Canopy
fixed wireless
Zigbee
Z-Wave
Bluetooth
mobile phone standards
wireless network interface controller
station
MAC addresses
Ad hoc mode
service set
SSID

Certification

The Wi-Fi Alliance was created in 1999 to help make sure Wi-Fi devices can work together and follow important rules. Only devices that pass their tests can use the Wi-Fi logo. These tests check that the devices follow safety and security rules.

Some Wi-Fi devices might not have this certification, but they can still work with other Wi-Fi devices. The Wi-Fi Alliance decides whether new names for Wi-Fi technology can be used.

Versions and generations

Wi-Fi has many different versions that help devices talk to each other. Each version works a bit differently, like using different types of radio waves or allowing faster data speeds. Some versions can use more than one antenna to make things even faster and clearer.

In 2018, the Wi-Fi Alliance made things simpler by grouping these versions into generations like Wi-Fi 4, Wi-Fi 5, and Wi-Fi 6. This helps people know which versions of Wi-Fi their devices can use. These newer generations can usually work with older versions, so everyone can still connect together.

Uses

Internet

Wi-Fi technology lets devices like laptops and phones connect to the Internet when they are close to a Wi-Fi router. This can work in homes, offices, coffee shops, and even whole cities. Some places offer free Wi-Fi, while others charge for it. Universities often have Wi-Fi across their campuses so students and teachers can get online.

City-wide

Many cities have built big Wi-Fi networks. For example, Mysore in India became the first Wi-Fi city in 2004. In the United States, St. Cloud, Florida and Sunnyvale, California started offering free citywide Wi-Fi in 2005. London planned to have citywide Wi-Fi by 2012, and New York City turned old phone booths into Wi-Fi hotspots called LinkNYC. Seoul in South Korea also worked on providing free Wi-Fi in many public places.

Geolocation

Wi-Fi can help find where a device is located when GPS isn’t good, like inside buildings. It uses the strength of Wi-Fi signals from known places to figure out a location.

Motion detection

Wi-Fi can also be used to detect movement and recognize gestures, like sensing if someone is walking by or waving their hand.

Operational principles

Wi-Fi allows devices like computers and smartphones to talk to each other by sending small packets of data through the air. These packets travel using radio waves, which are like invisible waves that carry information. Different types of Wi-Fi use different methods to send these waves, some using a technique called "spreading" the signal out, while others use "dividing" the signal into smaller pieces.

Wi-Fi works on specific radio frequencies, like the ones you might hear from a microwave or a cordless phone. These frequencies are split into channels, which are like different lanes on a road. Devices can share these channels, but they have to take turns to avoid bumping into each other. Each device has a unique address, kind of like a name tag, that helps make sure the right packets go to the right place.

When many devices are using Wi-Fi at the same time, they might sometimes bump into each other’s signals. Wi-Fi has a way to handle this by having devices wait and try again if they sense the air is busy. This helps keep things running smoothly, even though it can sometimes slow things down a bit.

Waveband

The main frequencies Wi-Fi uses are 2.4 GHz and 5 GHz. The 2.4 GHz band can reach farther but doesn’t have as many channels, while the 5 GHz band offers more channels for faster speeds but doesn’t go as far. Different countries have different rules about which channels can be used and how strong the signals can be.

Communication stack

Wi-Fi is part of a bigger set of rules called IEEE 802, which helps devices talk to each other. Wi-Fi adds special rules to handle the fact that wireless signals can get mixed up or lost. This means Wi-Fi doesn’t always guarantee that every packet arrives perfectly, but it has ways to check and fix problems if they happen.

Modes

Most Wi-Fi networks use a base station, like a router, to manage communication. This makes it easier for devices to talk to each other because they all go through the same point.

Wi-Fi can also work without a base station, letting devices talk directly to each other. This is useful for things like multiplayer games on handheld consoles or sharing photos from a camera.

Having multiple base stations can make a Wi-Fi network stronger and cover more area, which is helpful for big places like schools or offices.

Performance

See also: Long-range Wi-Fi

Wi-Fi works best when there are no big obstacles like walls or metal between devices. The distance Wi-Fi can reach depends on things like how strong the signal is, the type of antenna used, and what’s around it. Sometimes, Wi-Fi can go very far—over 30 kilometers with special antennas!

Wi-Fi uses multiple antennas to improve its speed and reach. This helps it send information faster, even in crowded places. However, Wi-Fi can sometimes get slower if there are too many devices nearby or if other gadgets, like microwaves or Bluetooth, are using the same radio waves.

Hardware

Wi-Fi lets devices connect to each other without wires. This is useful in places where running cables is hard, like outside or in old buildings. But thick walls can block the Wi-Fi signal.

Most laptops today have built-in Wi-Fi, and the cost to add Wi-Fi to other devices keeps going down. Wi-Fi devices can talk to each other all over the world, unlike mobile phones. A wireless access point links many wireless devices to a wired network, acting like a hub. Wireless adapters help devices join a Wi-Fi network, and many new laptops have these built-in. Wireless routers combine several functions, letting both wired and wireless devices connect to the internet through one easy-to-use program.

Security

Main article: Wireless security

Wi-Fi networks are easier to access than wired networks because you only need to be close enough to the network to connect. This can make it harder to keep information safe. To help protect data, many Wi-Fi networks use special codes called encryption to keep messages private.

There are different ways to make Wi-Fi more secure. One way is to hide the network name, but this isn’t very effective. Another method is to only allow certain devices to connect, but someone could pretend to be one of those devices. Older security methods like WEP aren’t safe anymore because people can easily break them. Newer methods like WPA2 are much safer and are used by most modern devices. However, even WPA2 can have problems, so it’s important to use strong passwords to keep networks secure.

Societal aspects

See also: Internet § Social Impact

Wireless Internet access has become a normal part of everyday life. It has changed how people live and work in many ways.

Influence on developing countries

See also: Long-range Wi-Fi

In many parts of the world, especially in rural areas, people did not have access to the Internet. Some of these places use special Wi-Fi networks that can work with solar power. For example, in Peru, a long Wi-Fi network uses solar panels to connect a hospital to smaller medical stations, helping people far away get medical care.

Work habits

Having Wi-Fi in public places like cafes or parks lets people work from almost anywhere. Many people choose places with Wi-Fi so they can work while enjoying other things around them. Working with Wi-Fi also lets people move around more freely, whether they are at home or in an office.

Housing

Most homes today have Internet access, and many use Wi-Fi. This has changed how people use their homes. For example, some people like to work in different rooms of their house instead of just one office. Even hotels have noticed that guests pick rooms with better Wi-Fi signals.

Health concerns

Further information: Wireless device radiation and health

The World Health Organization says that no health effects are expected from exposure to radio waves from Wi-Fi networks, but they encourage more research on other sources of radio waves. The International Agency for Research on Cancer has said that radio-frequency electromagnetic fields might possibly cause cancer, but this was based on studies about cell phones, not Wi-Fi.

Studies of people who think they are sensitive to electromagnetic fields show that their symptoms are not caused by the fields themselves, though more research is needed.

Alternatives

There are several other wireless technologies that can be used instead of Wi-Fi for different purposes. For example, Bluetooth Low Energy and regular Bluetooth are good for short distances, while Cellular networks are used by smartphones. LoRa and WiMAX are designed for longer distances, and Zigbee is great for low-power, short-distance communication.

Some technologies can use existing wires in your home, like G.hn, which uses phone or power lines. There are also wired options such as Ethernet over twisted pair, which can be a good alternative to wireless connections.