Back cover: Used to cover your battery, SIM card, and SD card.
Camera: Used for taking pictures.
Flash: Used for taking pictures in low-light situations.
Power/Lock button: Wakes the touchscreen or puts it to sleep when you press it. Turns the device completely off or on when you hold it down.
USB/Charging port: Connects your phone to the battery charger or to another device for transferring data.
Volume buttons: Lets you adjust the device volume.