Computer memory

RAM

RAM (Random Access Memory) is temporary storage. It stores data and programs that are currently being used by the CPU. RAM is volatile memory, which means the data disappears when the power is turned off

ROM

ROM (Read Only Memory) is permanent storage. It stores important instructions needed by the computer, such as BIOS. ROM is non-volatile memory, which means the data remains even when the power is turned off

Difference between RAM and ROM

RAM = temporary, fast, working memory

ROM = permanent, stores startup instructions

Virtual memory

When RAM is not enough, the operating system uses part of the hard drive as virtual memory. This area is called a swap file or paging file. However, using virtual memory may reduce computer performance because storage is slower than RAM.

Example, 

RAM full → computer borrows space from storage

This helps, but the computer may become slower