ClearType is Microsoft's marketing term for Windows' implementation of SubPixelAntiAliasing.
Useful, if not Linux-oriented information: you can activate ClearType support on your copy of Windows XP by going to Start menu -> Control Panel -> Display, clicking on the "Apperance" tab, and clicking on "Effects...". Check the box next to "Use the following method to smooth the edges of screen fonts" and use the drop-down menu to select "ClearType".
Looks best on LCD screens.
One page links to ClearType:
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