Movement of organisms to locations that are new to them.

This typically occurs during the of organisms, which typically occurs when they are small, motile, or both. Dispersal thus is associated with spores, zoospores, seeds, during , or, for many vertebrates, following the cessation of .

Dispersal and its consequences is a important component of biogeography. It is also relevant to allopatric speciation as a lack of ability to disperse from one location to another is equivalent to there existing a geographical barrier between those two locations (thus giving rise to geographical isolation.