So far, affecting only computers running Microsoft Windows, spyware is loosely defined as software that is installed on a target’s computer without their knowledge, and the software itself listens for interesting things (websites visited, passwords entered, and the like) and records these things, possibly sending the information back to some other host on the internet.

Spyware is widely considered to be the most problematic thing about the Internet today, though one could run Linux on the same hardware, or Mac OS X on different hardware, and be safe (at least, today).