linsys network question

I'm very new to wireless internet. I just got a new powerbook and imac. At home, both are connected to my network over an airport extreme router.

When I take my powerbook anywhere, I can connect to the internet via "linksys" network in my airport pulldown.

I'm just curious as to what it is and how i'm actually connecting.

it just means that theres a wireless network somewhere close from a linksys router