Overview of storages and partitions of Android

Storages
There are ram, flash memory and sd card. Generally, ram is the fastest and sd card is the slowest.

Common partitions

• splash1
• boot
• kernel
• recovery
• system
• essential software
• For example, CyanogenMod is installed to this.
• Generally speaking, this is write-protected.
• cache
• data

Rom
The term 'ROM' has multiple uses in the Android world, and it gets misused a lot. Mostly, ROM means the system partition.


References
http://wiki.cyanogenmod.com/wiki/Overview_of_Modding