Computer memory, also known as RAM, is temporary storage that allows the computer to perform tasks by holding instructions and data in an easily accessible location. There are two main types of computer memory: volatile and non-volatile. Volatile memory, like RAM, loses its contents when power is removed while non-volatile types like ROM retain data without power. Over time, RAM technologies have evolved from SIMMs to DIMMs and SDRAM to DDR, DDR2, and DDR3, with each generation offering faster speeds and higher capacities. Proper identification and installation of the correct RAM type is important for system functionality and performance.