iPhone has an internal rechargeable battery.

For important safety information about charging iPhone, see the Important Product Information Guide.

Charge the battery:
Connect iPhone to a power outlet using the included USB cable and power adapter.

iPhone connected to power adapter

Charge the battery and sync iPhone:
Connect iPhone to your computer using the included USB cable. Or, connect iPhone to your computer using the included cable and the Dock, available separately.

Unless your keyboard has a high-powered USB 2.0 port, you must connect iPhone to a USB 2.0 port on your computer.

iPhone connected to Mac

IMPORTANT: “iPhone 3G” cannot be charged with a FireWire power adapter or FireWire-based car charger. If iPhone is connected to a computer that’s turned off or is in sleep or standby mode, the iPhone battery may drain.

An icon in the upper-right corner of the screen shows battery charging status.

battery charging and charged iconsIf you charge the battery while syncing or using iPhone, it may take longer to charge.

IMPORTANT: If iPhone is very low on power, it may display one of the following images, indicating that iPhone needs to charge for up to ten minutes before you can use it. If iPhone is extremely low on power, the display may be blank for up to two minutes before one of the low-battery images appears.

low-battery imagesRechargeable batteries have a limited number of charge cycles and may eventually need to be replaced. The iPhone battery isn’t user replaceable; it can only be replaced by an authorized service provider. For more information, go to www.apple.com/batteries.

http://www.apple.com/iphone/tips/