Well, here's the quicky laymans definition:
An Infinite Baffle ("IB") is a speaker that keeps the rear wave (everything behind the cone) from entering the listening area. It requires you to have a hole known as a 'throat' that focuses the sound into the room, but sends the rear wave into an attic, basement, outside, or another room. The cubic area of the area that contains the rear wave should be at least 10 times the Vas of the drivers used (ideally). Some folks say you can get as low as 5x Vas, but the purists say ten. Mine is just a hair under 5x.
An IB consists of even amounts of large drivers (15" & 18" are most popular).
The "guru's" of IB have a forum with lots of juicy photos. The site is
> HERE < and is called "the cult of the infinitely baffled".
Another advantage of IB is the box doesn't have to be pretty, or fancy looking. It's hidden away in another area. The opening of the throat is covered by a decorative grate. That's the only thing that can be seen from the listening area. So good carpentry skills are optional.

Bob
EDIT: Ahhh crap.....I didn't catch the comment about portability.

Good catch Lin.
Well Mr. K__x, when your'e ready to have system that's NOT portable, check into IB.