Biodiversity is the variety of species, their genetic make-up, and the natural communities in which they occur. It includes all of the native plants and animals in Pennsylvania and the processes that sustain life on Earth. Pennsylvania is home to over 25,000 different species of organisms, and of this total, over 800 are considered to be rare, threatened, or endangered. For many groups of organisms, such as insects, fungi, and algae, very little is known about them – not even what species occur in Pennsylvania! The need to understand the state’s rich natural resources has never been more critical.