TreeBASE provides a mechanism to discover what is known about phylogenetic relationships through access to published phylogenetic studies and the data and trees that these contain. TreeBASE can be used: to locate information on the phylogeny of particular groups of interest. to obtain datasets for studies of character evolution, including general patterns across many groups, such as patterns of homoplasy. in studies of biogeography -- to retrieve trees with representatives in particular geographical areas. in studies of coevolution -- to retrieve information on host and parasite phylogenies. in studies of congruence and combination of data -- to retrieve all molecular and morphological phylogenies for particular groups. in studies of phylogenetic methods -- to retrieve all parsimony or maximum likelihood reconstructions, for example, or to download datasets of various sorts to test methods. to link together trees of particular groups into more inclusive phylogenies. to discover understudied groups -- a resource for students, funding agencies, etc. to retrieve phylogenetic information for use in conservation biology and the management of natural resources.