PHYLIP (the PHYLogeny Inference Package) is a package of 35 programs for inferring phylogenies (evolutionary trees). Output is written onto special files with names like "outfile" and "outtree". Trees written onto "outtree" are in the Newick format, an informal standard agreed to in 1986 by authors of a number of major phylogeny packages. PHYLIP is probably the most widely-distributed phylogeny package. It is the sixth most frequently cited phylogeny package, after MrBayes, PAUP*, RAxML, Phyml, and MEGA. PHYLIP is also the oldest widely-distributed package. It has been in distribution since October, 1980, and has over 30,000 registered users. It is still being updated.

The author of this package is Joseph Felsenstein, Professor in the Department of Genome Sciences and the Department of Biology at the University of Washington, Seattle.