An open system
Google gives Android to manufacturers for free (the AOSP base is open source). Samsung, Xiaomi, Motorola and others customise it. That is why there are Android phones at 100 and at 2,000 euros. Services such as the Play Store, however, require a licence agreement with Google.
Named after sweets
Until 2019 Android versions were named after desserts in alphabetical order: Cupcake, Donut, Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwich, Jelly Bean, KitKat, Lollipop, Marshmallow, Nougat, Oreo and Pie. Since Android 10 only numbers are used.
Android today
Android also runs in watches, TVs, cars and foldable phones. The biggest challenge is fragmentation: older phones often stop getting updates, so check how many years of support the maker promises.