Most consumers are familiar with the 802.11 standards; however, this new sequential number rebranding is intended to simplify things. Previously, the naming design used the alphabet, starting with a to bto g and n, with each one representing the next generation. We'd expect z to be the last or fastest one, or until they have new names, but suddenly we're on 802.11ac, which is faster than all previous versions, so it's understandable that users would be a bit confused. Thus, starting from 802.11n, Wi-Fi will be referred to as Wi-Fi 4, 802.11ac as Wi-Fi 5, and 802.11ax as Wi-Fi 6.

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WiFi 6: higher data rates, increased capacity, enhanced performance in dense environments, and improved power efficiency. Operating on the same 2.4 GHz and 5 GHz band as Wi-Fi 5, Wi-Fi 6 is rated to support transfer speeds of up to 10 Gb/s, which ranges from four to ten times faster than the current standard.

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802.11ax utilizes OFDMA (Orthogonal Frequency Division Multiple Access), one of the big advancements with LTE technology.

TL;DR: less congestion in crowded networks and better speeds.