"A technique used ... to make diagonals ... appear smoother" [L1 ]. Commonly applied nowadays in typograpy: "The most common example is black characters on a white background."
[... relate to TkGS, Good Looking Tk, Nextgen Tk, Revitalized Tk, Xft support, ...]
Antialiasing is not an unalloyed good, as Joel, for example, recognizes in his "Three Wrong Ideas ..." [L2 ].
DKF: I'm not sure that I agree with Joel. But bad antialiasing isn't worthwhile, I'd agree.
KPV: Of course its a matter of taste, but I've never liked antialiased fonts. I find that they seem to have a blurry color to them which I find distracting.