I want to root my verizon wireless samsung galaxy s3 but I've heard that you have to "unlock" your phone before you can root. I'm not exactly sure what unlocking is. I'm confused as to whether I have to unlock my bootloader first or unlock my sim card so that it can work across multiple carriers in order to root my phone. I'm planning on using this (How To Root Verizon Samsung Galaxy S3 4.1.1 & Install CWM Recovery! SCH-I535 - YouTube) guide to root my phone but I need to know if I have to unlock my phone first and how I should go about unlocking it.