More on Drives: For the past few years you have been able to buy a portable Hard Drive that plugs into a USB port on the computer. This is in addition to the "Hard Drive" already iside the computer. Both floppy drives and Hard Disk Drives use tiny pulses of magnetism to store bits of computer information (data) on material that can hold the magnetism. Later, if you want, you can tell the computer to erase that data, or tell it to add more data to it.

In a disk drive, there is a small "magnetic head" that has electromagnetic coils in it, that slides across the surface of the magnetizable material. Actually it is not right on the surface, but a teeny-tiny-itty-bitty bit above the surface.A few microns. The head leaves magnetized bits of data on the material when it records , or "writes" the data on the disk drive. To get the data back out of the computer's disk drive, the same magnetic head goes back and picks up (or "reads") the magnetized bits of data that got left there and sends them to the CPU.

(If you want to know more about how much data, and how much data is stored, click "Bits and Bytes".)