HOW THE COMPUTER MEMORY WORKS?
The first large size random access memory in computers was based on magnetic cores; depending which way was "North", the data was 0 or 1.
This is a 32 Kilobyte unit, with about a quarter of a million individual ferrite rings, one per bit:
https://flic.kr/p/2ivfr3V
https://flic.kr/p/2ivcTtU
Bistables (flip-flops) were used for small amounts of data such as CPU registers - originally using relays or valves (vacuum tubes) then by the late 50s / early 60s, transistors.
That's "Static RAM" - it holds its state until as long as power is on, until made to change.
This is a board with three flip-flops, so three bits of storage (with lots of those, and many other logic circuits) used in the computer, plus core memory:
When integrated circuits could be made complex enough, the flip-flops were built in larger quantities in ICs - eg. an early RAM IC was typically 256 bit, then 1K, 2K and so on. You can now get static RAMs with eg. four megabits storage in a single IC.
Dynamic RAM was next, with each bit stored as a high or low voltage on a capacitor. That has to be "refreshed" continuously, with each row of data cells being read and re-written every few milliseconds to maintain the correct high or low state on the capacitors.
That's the type used in PCs and such today as main memory - the RAM ICs on the modules that fit the main board.
Plus there are other types of memory such as ROM, PROM, EPROM, EEROM, Flash ROM - all types that do not lose data when power is switched off, but either the content cannot be changed at all, (ROM / PROM) or takes special equipment or a special program sequence to change any of the data content; it's also generally far slower than RAM.
That's what is used for such as the "boot code" or BIOS in computers, with Flash memory used for things like SD cards and as the main storage (instead of hard disc drives) in such as smartphones, tablets and solid-state drives (SSDs).
[Edit - I was trying to keep the photos as links, but it's auto expanded them...]