Official firmware is put out by Sony themselves, and that's what you update to when you are prompted to update in order to play SEN. OFW can be modded, which then turns to MFW, or CFW. CFW. CFW stands for custom firmware. Most of the time you see a PS3 Jailbreak 4.83 CFW, especially for newer firmwares above 3.55, they are a spoof.