How to enter Recovery and Download Modes on Samsung Galaxy S3

How to get into Recovery Mode

1. Unplug the USB cable.
2. Shut down the phone.
3. Hold down the 'HOME' + 'VOLUME UP' buttons and press the 'POWER' button for about 5 seconds to enter Recovery Mode.

How to get into Download Mode (eg: for Odin)

1. Unplug the USB cable.
2. Shut down the phone.
3. Hold down the 'HOME' + 'VOLUME DOWN' buttons and press the 'POWER' button for about 2 seconds until a WARNING! Screen appears. Press the 'VOLUME UP' button to enter Download Mode.
4. To get out of Download Mode, simply press and hold the power button until the phone restarts