Postby blkmage » Wed Apr 29, 2009 4:53 pm
Both are related to typography, so pretty much anyone who isn't involved with web design will probably not be excited by it.
Kerning controls the space in between characters in a font. In most fonts, where the width of each glyph is different, it's important since certain pairs of letters will look awkward if the spacing is the same. For example, the space between A and V (AV) should be different from the space between S and T (ST). Each font usually contains a table of these pairs.
Ligatures are alternate glyphs for characters who interfere with each other. For example, in a lot of fonts, the curved part and cross in f and the dot of i are really close together. It's usually replaced with fi. Other pairs of characters are ff, fl, and fj. Historically, & was a ligature of 'et' which was latin for "and".
Until recently, most programs didn't support these. It wasn't until Office 2007 that they recognized ligatures. Usually, it was design programs, like Illustrator and InDesign, or typesetting programs, like LaTeX, that would worry about stuff like proper typography. It's something that a lot of people who have moved from print design to web design would be happy about.