Posted by Jayce Ooi as How to
How to install firmware on Samsung Galaxy S III? There are several ways to install firmware on Samsung Galaxy S3 no matter official or custom firmware in tar (or .tar.md5) format. Personally, I still prefer to install Samsung Galaxy S3 firmware with Odin. No need to wait for official firmware release through OTA and Samsung Kies. I can install leaked Samsung Galaxy S3 firmware with Odin. Or try out other region firmware.
Note – You should not face any issue when upgrading to newer official firmware. Your applications and data will be intact. However, you will need to factory reset when you downgrade firmware to older version because you might face boot loop issue. Therefore, make sure you make a backup before install new firmware.
Step by Step Guide