What's an invasive species? It's a great question and one that is much more complex than one might think. The United States Department of Agriculture has created the online National Invasive Species Information Center (NISIC) to bring together key resources on these types of species in the United States as well as other corners of the world. On the site, visitors can Browse by Subject to find Aquatic Species, Plants, Animals, and Microbes. In each of these areas, visitors can read the legal definitions of these species and also use the search feature to look for additional resources. The Spotlights area also contains a useful interactive learning module, a calendar of related conferences, government bills, and funding resources.