Internal and External Storage

Secondary storage keeps programs and files while the power is switched off. The device that does the storing can be internal, built into the computer, or external, plugged in only when you need it.

Internal storage

An internal device is fitted inside the computer's case and connected to the motherboard. A desktop tower might have a hard disk screwed into a drive bay beside a solid state drive slotted into the board, while a tablet has its storage sealed inside with no way to swap it.

• Nothing sticks out, so a laptop still slides into a bag easily.
• It cannot be left behind or unplugged by accident, and the connection inside the case is quick.
• There is nothing extra to carry, but the storage belongs to that one machine, so sharing a file means sending it over a network.

External storage

An external device sits outside the computer and is connected when it is needed, most often through a USB port. A pocket-sized drive or a plug-in solid state drive works this way: you plug it in, the computer detects it, and it appears as an extra drive you can save to.

• A band can record its tracks in a studio, then take the drive to a friend's house and carry on mixing them on a different machine.
• Extra space is added without opening the case, and the device can be locked away from the computer.
• The cable link is usually slower than the connection inside the case, and a small device is easy to lose, drop or knock out of its port mid-save.

The same device in two forms

Internal and external describe where a device sits, not what it is made of. A DVD drive can be screwed into a bay at the front of a tower or sold as a slim box that plugs into a USB port; the laser and the mechanism inside are identical, and only the casing and the connection change.