Random Access Memory or RAM is a form of computer data storage. A random-access memory piece allows data within a computer to be accessed in relation to its physical location of the data inside the piece of memory.
ROM
Read-only memory or ROM is a class of storage used in computers. Data stored in ROM can only be modified slowly with difficulty. Because of this it is mainly used to distribute firmware.
Cache
Cache is a component that stores data so future requests for that data can be served faster, the data within a cache might be there because of a previous computation or a duplicate of data elsewhere.