Connectivity: Bluetooth (syncing), SIM card slot (4G/2G), Wi-Fi (on some advanced models).
Communication: Make/receive calls, send texts, receive notifications.
Health & Fitness: Pedometer (steps), Sleep Monitor, Heart Rate Monitor, Blood Oxygen (SpO2).
Multimedia: Built-in Camera (often low-res), Music Control, Audio Player, Video Recording (sometimes).
Utilities: Alarm Clock, Calculator, Calendar, Flashlight, Anti-loss features.