And just to confuse things further, people very often say coil tapping when they mean coil splitting.
Coil splitting is switching off one coil of a humbucker to give a single-coil tone. This again lowers the output of the pickup and gives a thinner, brighter tone which resembles a Fender-style single-coil but is often rather weedy and unsatisfactory due to the humbucker's different magnetic structure.
Coil-split switches are very common on production guitars, series/parallel or coil-tap switches are much rarer. Personally I like series/parallel because it's a different, useable humbucker sound rather than a poor "imitation" of a single-coil. And it works particularly well with high-output humbuckers.