Computer memory facilitates short-term data access while computer storage enables long-term data access. Storage includes drives (solid state, flash, optical, hard) and memory includes DRAM, SDRAM and RDRAM chips that lose their stored data immediately after the computer is turned off.
Data stored on the hard drive is permanent and remains intact even when the computer is turned off. If a file is deleted, only the path to the file is removed but not the data itself. That is why it's possible to retrieve deleted information from a hard disk. The only way to permanently delete a file is by formatting the drive.
Memory facilitates the quick access of files from the hard disk. When an application is run, the processor retrieves the data from the hard drive and instantly loads it to the RAM. The amount of RAM a computer has determines how many applications can run simultaneously. When a computer's hard drive space is designated to act like RAM, it becomes virtual memory. Virtual memory can be used to improve performance when there is insufficient RAM.
Computers also have a tiny amount of Read Only Memory (ROM) that contains semi-permanent or permanent instructions required to start up the computer and check hardware components. An example of information stored in ROM is the BIOS.