Computer memory is any physical device capable of storing information temporarily or permanently. There are two types of computer memory Primary Memory or Main Memory whicn include RAM (Random Access Memory) & ROM (Read Only Memory) and Secondary Memory or Auxiliary Memory which include Magnetic Disk, Magnetic Tape, Optical Disk etc.
Random Access Memory (RAM) - is a type of volatile memory that is stores information on an integrated circuit which hold the data mainly when the program is being executed by the CPU. As it is volatile in nature so it can't store data permanently.
Read Only Memory (ROM) - a non-volatile memory chip in which data are stored permanently, and can not be altered by the programmer.
A storage, which suppliments the main memory of a computer. Often refferred to as secondary storage, this section of computer's memory is non-volatile and has low cost per bit stored, but it generally has an operating speed far slower than that of the primary storage.
A small high speed memory, which is used to increase the speed of processing by making current programs and data available to the CPU at a rapid rate.