Samsung Galaxy S III Android system recovery <3e> mode is a simple recovery mode that comes by default. It may not have lot of features compare to ClockworkMod Recovery Mode. But it does have the ability to perform several simple tasks like apply update from external storage, wipe data/factory reset, wipe cache partition, apply update from cache and reboot system now.
Samsung Galaxy S3 Android system recovery <3e> mode
How to load Samsung Galaxy S3 Recovery Mode?
step1.Turn off Samsung Galaxy S3.
step2.Press and hold down Volume Up + Home + Power buttons at the same time.
step3.Release all buttons when you see SGS3 Logo.
step4.Android system recovery will be loaded then.
It is always recommended to perform wipe data / factory reset and wipe cache partition before install new Android ROM. So recovery mode will be useful then.