Great question! But first, let's back up...

​

All living things are made of cells that contain DNA molecules, and differences in the size and sequence of these molecules between individuals and species generates all of Earth's biodiversity.

​

All living things shed bits of their DNA into the environment (think hair and skin cells for humans), and these fragments can stick around for a while depending on how fast they degrade.

​

Scientists can collect DNA fragments from the environment very easily - in soil, water, air, etc.

​

Powerful DNA sequencing tools allow us to determine the origin of this 'environmental DNA', like whether it's from a particular species or even from unique individuals of the same species.

​

In this way, environmental DNA is a valuable source of information about species presence and biodiversity in all kinds of places.