From blog.malwarebytes.com
In April of 2021, Apple introduced AirTags to the world, making the small tracking devices—similar to a Tile— available for purchase at the end of that month. The circular, coin-like product is designed to be attached to or placed in objects that are commonly lost, such as keychains, wallets, purses, backpacks, etc.
You can track an AirTag with your iPhone in some powerful ways, enabling you to locate a set of keys that has fallen down between the cushions of a couch, for example. You can see its location on a map, and if you’re close to it, you can get a directional signal on newer iPhones. It can be put into lost mode, enabling someone who finds it to tap it with their phone and get information you supply, such as a phone number to call.