Rom

[mattatwar]

What is a custom rom?

 

[fatboy97]

It's a ROM that is built for a device that is not the stock ROM... it usually has some unique ways of setting up the ROM. It might also contain a custom kernel, which might be able to be overclocked.

 

[PvilleComp]

What is a custom rom?

If you're looking for more detail and a really informative read - check out this thread by Jerry.

http://forums.androidcentral.com/hacking/6037-general-rom-faq.html