How does solid-state memory work?

I am aware that portable MP3 players n’stuff have huge amounts of available space and take up little energy because they utilize solid-state memory. A yahoo search was inconclusive. So, what is solid-state memory, and how does it work?

How’s this?

So much more efficient than vacuum-tube memory.

Where have you seen it called “solid-state memory”? As far as I know, the term “solid-state” hasn’t been used much since the 70s, when they were trying to differentiate a product from one using vacuum tube electronics. Solid-state meant that they used transistors.

MP3 players have benefitted from the increasing density of computer memory, which comes from many very smart people figuring out how to make little electronic circuits even tinier. It wasn’t that long ago that even unix computers didn’t need 64 MByte disk drives, now that’s not even enough RAM to run a PC. I did all my college computer work on a machine with 196 K of core (made with little doughnut-shaped magnets) memory.

Does anyone remember when memory was made with magnet rings that was about the size of small beads and had wires running through it in 3 directions…?
Jim