root access - What is the difference between: Rooting, Jailbreak, ROM, Mod, etc.?

What is the difference between:

• Unlocking the bootloader (prerequisite for doing many, though not all, other things below)


• Rooting


• Jailbreaking


• ROM


• NAND and Nandroid


• Operating System


• Mod (e.g. CyanogenMod)


• Recovery (ClockworkMod, Amon Ra)


• Custom Kernel (e.g. LeshaK's kernel)


• Firmware



• Driver


• Over The Air (OTA) update


• Fastboot


• SIM unlocking


• Flashing


• SPL (Second Program Loader)

(any other often-confused terms that I've missed?)