Trackstick is a USB Key-like device, ie, a device that plugs into your computer's USB port. When you're not connected to your computer, you can record your position in real time.
The Trackstick carries between 1 and 4 Mb of flash memory, enough to store up to one month of tracks. The Trackstick is a GPS without all the "stuff" (like a monitor, buttons, antenna, etc). You switch it on, and it records where you are with GPS accuracy.