The USB port on your laptop allows for a variety of gizmos to be attached without needing a specific port or bulky connector. This is a major improvement over earlier portable computers that needed to sport two COM ports, one printer port, plus other obscure ports, each designed for specific hardware. The below table lists the most common uses for the USB port on your laptop.

Device Typical Boring Usage
External storage Includes external hard drives, CD/R, DVD, and flash memory storage options.
Printer Prints stuff on paper.
Scanner Sucks images from flat surfaces and reproduces them as graphics inside the computer.
Network adapter Simply provides, through the USB port, another way to add networking to your laptop (although a PC Card network adapter is recommended over USB because the PC Card adapters fit better).
MP3 player Beams music between the laptop and the player. Note, though, that a laptop by itself with a set of headphones works like an MP3 player.
Digital camera Lets you grab photos from the camera's memory card and store them on the laptop. This can also be done directly, by removing the camera's digital storage media.