For Verizon, please see How to Root Verizon Galaxy S3 SCH-I535 instead!
So, let’s root our Galaxy S3, it only takes about 5 minutes, very safe to do.
Before we begin, you will need a Windows computer (For Mac, please see How to Root Galaxy S3 on Mac OSX! and For Linux, please see How to Root Galaxy S3 on Linux/Ubuntu!), micro-USB cable, and make sure your phone has at least 50% charge.
Step 1. Hold down Volume Down, Home Center, and Power buttons together for about 20 seconds until your phone resets and shows you an option to get into download mode.