Phylogeography: (n) the study of the historical processes that may be responsible for the contemporary geographic distributions of individuals
By comparing modern and ancient Y-DNA, anthropologists have determined the likely migration path of each haplogroup out of Africa 70,000 years ago up to the last 10,000 years (above).
Each haplogroup in the above map has, in the past few thousand years, split into dozens if not hundreds of subclades (separate lineages derived from a common ancestor). Each of these lineages has its own unique migration path.
The goal of the PhyloGeographer project is to determine migration paths of more recent Y-haplogroups than is currently known.
This is possible because haplogroup project administrators have access to increasingly more and better data than the scientists did that created the map above. PhyloGeographer gives them a way to compute migration paths and share them with project members.