The Samsung Galaxy S3 has been the most anticipated phone for the year 2012 and it has now been rooted. Rooting will give you superuser access that will allow user to perform administrative tasks such as modifying data in locations that is otherwise prohibited. You will also be able to overclock and underclock to boost performance and battery respectively.
To perform root on the Galaxy S3, download this file and extract it. After that, start install.bat file and follow the instructions on the screen. In the background, it will install superuser APK file and perform rooting on your Galaxy S3. Also check out the Samsung galaxy fit root guide.