"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. To me they seem to have a blurry color which I find distracting.
WJR: When it's done right, antialiasing can result in better readability and comprehension. I'll dig up some references that attest to this, but I seem to remember an article by Jakob Nielsen discussing Microsoft's ClearType technology.
KPV Information on Microsoft's ClearType can be found at [L3 ], including the article by Jacob Nielson [L4 ] which claims that ClearType will make this user at least 10% more productive while reading from the screen. I reiterate but in my last job I looked into ClearType and for me it would 10% less productive. YMMV
TV In computer graphics, anti-aliasing is usually to prevent artifacts in images which usually become indeed neater to look at in the process, for instance when a ray-tracing image 'shoots' more than one ray per image pixel to make edges not artificially 'gridded' to the pixels in the image. The colouring can be a result of an antialiasing, or resolution enhancement simulation making use of the fact that pixels on a CRT or other screen are composed of usually red, green, and blue, which are arranged in some constellation per image pixel, and the per colour pixels are 1/3 of the size of a 'whole' image pixel. Alternatively, it could be that a screen with a small number of RGB quantisation values, or a small colour table (or software which runs on a better screen but thinks/acts limited) does a bad job at creating intermediate grey levels by setting unequal rgb components.
Anyhow, relation with tcl/tk, uh, Tk issues, theming and visual appearance issues.