The Extended Speech Assessment Methods Phonetic Alphabet (X-SAMPA) is a variant of SAMPA developed in 1995 by John C. Wells, professor of phonetics at the University of London. It is designed to unify the individual language SAMPA alphabets, and extend SAMPA to cover the entire range of characters in the International Phonetic Alphabet (IPA). The result is a SAMPA-inspired remapping of the IPA into 7-bit ASCII.
SAMPA was devised as a hack to work around the inability of text encodings to represent IPA symbols. Later, as Unicode support for IPA symbols became more widespread, the necessity for a separate, computer-readable system for representing the IPA in ASCII decreased. On the other hand, X-SAMPA is still useful as the basis for an input method for true IPA.