Primary storage device
A primary storage device is a medium that holds memory for short periods of time while a computer is running. Although it has a much lower access time and faster performance, it is also about two orders of magnitude more costly than secondary storage.
RAM (random access memory) and cache are both examples of a primary storage device. The image shows three different types of storage for computer data. Primary storage's key differences from the others are that it is directly accessible by the CPU, it is volatile, and it is non-removable.
A primary storage device may also be referred to as internal memory, main memory, main storage, and primary memory.