memory
(1) Because memory means "remembering," memory sometimes refers to stored data. However, this is incorrect when referring to computing devices because their basic operation is the interaction between storage (remembering) and memory (not remembering). Definition #2 below is the correct definition of memory.
(2) Random access memory (RAM) is the temporary workspace in every computing device from phones to desktop computers to mainframes. All processing takes place in memory, and the interplay between memory, storage and the CPU is how work gets done.
For desktop and laptop computers, memory capacity typically ranges from 4GB to 64GB (4-64 gigabytes), although large-scale computers can have hundreds of gigabytes and even terabytes. Smartphones and tablets generally have from 2GB to 16GB, although some models have more.
Memory Does Not Remember, But Flash Does
Memory loses its content when the power is turned off, but "flash memory," the storage technology in solid state and USB drives does remember. Flash memory turned out to be a terrible name because people confuse it with random access memory (RAM). See flash memory, dynamic RAM, memory card and storage vs. memory.
All Processing Takes Place in Memory
All program execution that processes data takes place in memory. A program's instructions are copied into memory from storage (disk and solid state drives) or the network. The instructions are extracted from memory into the CPU for execution. They direct the device to input data into memory, process the data in memory and output the results from memory.
Processing Means Calculate, Compare and Copy
All data are processed (calculated, compared and copied) in memory (see 3 C's). As programs and data are written into memory, the previous contents of that space are lost. After processing, any new data are output from memory to the screen and back into storage.
An Electronic Checkerboard
Data in storage (disks, SSDs, flash drives) reside in blocks (sectors) hundreds or thousands of bytes long. After the block is written into memory, the content of any byte or contiguous bytes can be calculated, compared and copied with other bytes in memory. This "byte addressability" is what makes it very different than storage. In this example of counting California records, a constant (blue) is compared with the state field. If equal, a constant of "1" is added to a counter (yellow). See byte addressable, constant and memory.
Memory Doesn't Remember
Memory loses its content when the power is off, so why call it memory? Because the first memory "did remember," but today's memory chips do not. However, for certain unchangeable functions, there are memory chips that do retain their content and remember (see ROM, UEFI and non-volatile memory). See storage vs. memory.
Memory Can Be Clobbered!
Memory is allocated by both the operating system and the applications but released when no longer needed. However, errant programs can fail to release memory, reducing the amount for other programs. Bugs in software can alter the wrong memory bytes creating erroneous values that can only be reset by powering the unit off and on to reboot, which clears memory. For example, rebooting a TV cable box or a washing machine does the same thing: it clears the computer's memory.
Other terms for the computer's main memory are RAM, primary storage and read/write memory. Earlier terms were core and core storage. See dynamic RAM, static RAM, core storage and memory module.