Ultra-wideband spreads a signal across a channel hundreds of megahertz wide and sends extremely short pulses. Because the pulse edges are sharp, a receiver can timestamp arrival precisely and compute distance from time of flight, something narrowband radios like Bluetooth cannot do with the same accuracy. The current standard is IEEE 802.15.4z, with a secure ranging mode that resists relay attacks.
In IoT the main uses are real-time location of tools, pallets and people inside factories and warehouses, keyless car and building entry where the system must know a phone is really at the door, and spatial awareness between consumer devices. UWB is usually paired with Bluetooth Low Energy, which handles discovery and pairing before the UWB ranging session starts. Costs are higher radio price and power, so it complements rather than replaces BLE in asset tracking.
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