Location-based applications require devices to know their position accurately, and IEEE 802.11az (Next Generation Positioning) was created to meet that need. Although the standard improves positioning in both sub-6 GHz and mmWave bands, centimetre-level accuracy is only achievable in mmWave thanks to beamforming information. The article explains the 802.11az mmWave positioning exchanges, line-of-sight assessment and security features, evaluates the achievable accuracy using a new trigonometric method that handles non-line-of-sight reflections off walls, compares it with advanced positioning solutions, and identifies open research challenges.