What is Random access memory (RAM)
This is a volatile memory (i.e. contents are lost when computer is switched off). A user can write or delete data and read the contents. Before a program can be ran it should first be loaded into RAM that allows CPU to access the program. Battery-backed RAMs overcome data loss on switching power off though are outside the scope of these booklets.
(NOTE: For completeness, it's worth mentioning that two types of RAM exist termed as SRAM (static RAM) and DRAM (dynamic RAM) - SRAM doesn't need to be constantly refreshed to retain its memory unlike DRAM. Also consider that computers use cache which is a part of memory made from SRAM. Memory caching works as programs generally access the same data or instructions over and over again. By retaining as much information as possible in SRAM, computer operates more quickly (cache is generally termed level 1, 2 or 3 (termed L1, L2 or L3)).