Up to Speed
Don't worry, this should bring you up to speed.
- Activate - to bypass the required iTunes signup.
- Jailbreak - to allow full write and execute privileges on the iPhone, iPod touch, iPhone 3G, iPhone 3GS, iPhone 4, iPhone 4S, iPad and iPad2.
- Unlock - to allow the use of any mobile phone carrier's SIM.
If you want to get started, first you should listen to the 25C3 presentation "Hacking the iPhone". This was in 2008, but it explains the basics in detail. You should also learn assembler for ARM processors.