LZ78 compression
A {substitutional compression} scheme which works by entering
phrases into a dictionary and then, when a reoccurrence of
that particular phrase is found, outputting the dictionary
index instead of the phrase. Several {algorithms} are based
on this principle, differing mainly in the manner in which
they manage the dictionary.
The most well-known Lempel-Ziv scheme is Terry Welch's
{Lempel-Ziv Welch} variant of LZ78.
[comp.compression {FAQ}].