how do memory cards work? How do pm3 players store songs? How do video game systems stor memory?

i want to need how memory cards store memory and other things. i also need to know how mp3 players store songs and how magnetic tape works. and i need to know how game systems store memory for games. how do the memory cards work like for gamecube or play station
and how do gamee systems like the wii store the game memory on the wii system.