Wi-Fi is a trademark of the Wi-Fi Alliance. It can be used with certified products that belong to a class of wireless LAN, local area network, (WLAN) devices based on the IEEE 802.11 standards.
The wireless part of Wi-Fi refers to a low power transceiver using an unlicensed band of frequencies around 2.4 GHz. It competes with other wireless technologies in this space such as Bluetooth and your microwave oven. Since 2009 Wi-Fi has also been available on the 5.0 GHz band with much less interference.
A transceiver is located in your portable device and communicates wirelessly with a router which channels the information into a wired internet connection. It is mainly used in business, homes, and some commercial establishments like coffee shops and book stores. In the later case these places are called hotspots as they allow an Internet connection for all devices that are nearby. The connection may or may not be free of charge. Business and Home use is typically password protection to avoid use by unauthorized people and to provide security for the connection.
How Wi-Fi is performance is defined: If Wi-Fi was a highway, the specifications would be about a higher maximum speed limit for vehicles and about more lanes to handle more vehicles at once.
 IEEE 802.11
IEEE 802.11 is a set of standards that apply to wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. It uses techniques of spread spectrum and/or frequency division multiplexing to provide good local communication with low power devices. It defines both the hardware capabilities and the protocol to be used. It is subdivided into 3 groups based on the speed of the transmission for the 2.4 GHz band. (Other letters are used for additional capabilities, frequencies, and needs)
- a - The first Wi-Fi protocol appeared in 1997, offering 2Mbit/s link speeds.
- b - This is the slowest form currently in use. It has a maximum raw data rate of 11 Mbit/s. When it arrived in the years 1999/2000 and was faster than previous methods. It was quickly adopted as the baseline. Channel width is 22 MHz
- g - It appeared in June 2003 and operates at a maximum physical layer bit rate of 54 Mbit/s exclusive of error correction codes, or about 22 Mbit/s average throughput. 802.11g hardware is fully backwards compatible with 802.11b hardware but the protocol is different. Channel width is still 22 MHz.
- n - It first appeared in 2007 and was adopted in 2009. It is designed to improve network throughput over previous standards, such as 802.11b and 802.11g, with a significant increase in the maximum raw data rate from 54 Mbit/s to a maximum of 600 Mbit/s with the use of four spatial streams at a channel width of 40 MHz. Less streams and/or less channel width provides less speed improvement. The n group can also use 5.0 Ghz band. This was a significant step forward with the introduction of dual-band routers with both 2.4GHz and 5GHz bands. It could offer faster speeds at shorter ranges. It can also use Multiple Input Multiple Output (MIMO) technology, which uses several antennas to send and receive up to four spatial streams, resulting in enhanced performance. AKA known as Wi-Fi 4, it works on 2.4 GHz and 5.0 GHz bands.
- ac - The latest (as of 2018) and fastest Wi-Fi connection with 3X performance over the existing n service at up to 1750 Mbit/s. With 802.11ac in place the 5GHz band can push speeds of 1,300Mbit/s, so we’re talking speeds that are more than 600 times faster than they were in 1997. Wi-Fi ac, AKA Wi-Fi 5 only boosts performance on 5GHz band.
The speeds mentioned are theoretical maximums are are decreased by distance from the router and competition with other Wi-Fi users and nearby competing technologies in the frequency space.
 Wi-Fi 6
One of the most important changes Wi-Fi 6 brings with it is the new naming system. Using a simple succession of numbers is going to make it a lot easier for consumers to keep track of standards and make sure they’ve got compatible kit set up. The more technical term for Wi-Fi 6 is 802.11ax. Older standards are getting retroactively renamed too—the 802.11ac standard becomes Wi-Fi 5, the 802.11n standard becomes Wifi 4, and so on. Expect to see the new Wi-Fi 6 name on hardware products and inside software menus from 2019. Wi-Fi 6 performs on both 2.4GHz and 5.0GHz.
As always, the improvements with this latest generation of Wi-Fi are in two key areas: Raw speed and throughput. Wi-Fi 6 will support 8K video streaming, provided your Internet supplier is going to give you access to sufficient download speeds in the first place.
Wi-Fi 6 will provide the capacity, coverage, and performance required by users—even in dense environments such as stadiums and other public venues. Wi-Fi 6 networks enable lower battery consumption in Wi-Fi 6 devices, making it a solid choice for any environment, including smart home and IoT uses.
Key benefits of Wi-Fi 6 technology include:
- Higher data rates
- Increased capacity
- Good performance in dense environments
- Improved power efficiency
Two of its marquee features are multi-user, multiple-input, multiple-output technology (MU-MIMO), and something called Orthogonal Frequency Division Multiple Access (OFDMA). Basically, this technology enables more devices to simultaneously operate on the same Wi-Fi channel, which improves the efficiency, latency times, and data throughput of your wireless network. And while Wi-Fi 6 is designed to improve the performance of Wi-Fi networks on the whole, on your own device you might experience up to four times the capacity and four times the data throughput (the amount of data moved from one point to another) that you would with older wireless network standards; this could mean a throughput of 9 to 10 gigabits per second in optimal conditions.
Wi-Fi 6 provides the foundation for a host of existing and emerging uses from streaming ultra high-definition movies at home or on the go, to mission-critical business applications requiring high bandwidth and low latency, to staying connected and productive while traversing large, congested networks in airports and train stations.
 Wi-Fi Direct
WiFi Direct applies the Wi-Fi technology to allow point to point communication between two Wi-Fi enabled devices. It differs from regular Wi-Fi in that it doesn't need a router and is intended to allow device to device communication between devices that are not from the same manufacturer. It overlaps, to some degree, the capabilities of Bluetooth but is capable of a faster data rate.
 Wi-Fi Hotspot
A Wi-Fi hotspot is a device that can serve as the central router for a network. A standard router can be a Wi-Fi Hotspot but the term usually refers to a device such as a cell phone that provides the service using a cellular network. A Hotspot generally provides a connection to the Internet for all wireless connected devices but may also be used to provide a local network capability for these connected devices. For example a separate storage device may be able to stream movies or even eBooks to a local network of devices in a car while it is driving down the road. In this case it is behaving like a local cloud server.
The term W-iFi Hotspot can also be a reference to a public location, such as a restaurant or coffee shop, that provides an Internet connection for Wi-Fi enabled devices.