Indices : Terminology : Ligature

The connecting link between two letters that are joined together. Also, two or more characters that are combined into one Glyph, generally comprising such characters as , , , , etc.

When type was made of metal, ligatures were a physical necessity to stop one piece of metal clashing with another: it was physically impossible for strokes to overlap. Not so with digital strokes: so nowadays, ligatures have primarily aesthetic benefits. Some ligatures, such as the common may merely prevent the collision of two glyphs, but others such as the OO ligature provide a decorative, ornamental quality.

qu ligature, tell me why not? descends into a discussion of what comprises a ligature exactly.
Non-Latin Ligatures
Bring out Your Ligatures

Technical Discussion:
Unicode Ligatures

Additional Articles:
Wikipedia > Ligatures