Interactive Fiction is Text Adventures. I've written a few works of IF, but they're all quick, pointless, and full of in-jokes. Still, some people seemed to like them.
In order to play these games, you'll need a Z-Code interpreter. Conveniently enough, I've written one, which I like to call Viola.
On the other hand, Viola requires you to download Python and wxPython, which may not be so convenient. Also, it's full of bugs. All in all, then, you're probably better off grabbing an interpreter that works. You should be able to find such a beast here.
Written at the last minute for the IF Competition. A one-room game, more or less a parody of Zork-style games.
My first piece of IF! You know, the one most writers hide away and pretend never existed. Based on a throwaway joke from the Enchanter manual.