Ultra-wideband is a short range radio technology that measures the time a signal takes to travel, letting a device work out how far away and in which direction another tagged device sits, often to within a few centimetres. It now appears in many phones, trackers and car keys.
This precision enables useful tricks: pointing a phone to find a lost tag, unlocking a car only when the key is genuinely close, or handing off media to the right speaker in a room. Because it is accurate and hard to spoof from a distance, it is also valued for secure, location-aware access, though it needs matching hardware on both ends.