It's a mesh network that relies on beaconing to devices with Bluetooth enabled or more preferably Apple devices that are UWB-capable (U1 chip) which in return gives more precise tag localization. You can track tags from your either phone or tablet; these so far aren't visible on iCloud page IIRC.
I've got one but it seems to be activating only when Apple devices are around
Similar devices exist around - Samsung for example has own line of such tags
Basically most mobile Apple devices are enrolled in a network and anytime that an iPhone is near an Airtag, that network relays the location. It is essentially automated crowdsourcing of the location of stuff.
I've got one but it seems to be activating only when Apple devices are around
Similar devices exist around - Samsung for example has own line of such tags
https://en.wikipedia.org/wiki/Bluetooth_Low_Energy_beacon
https://en.wikipedia.org/wiki/AirTag