A plant or animal species can be a native, introduced, or invasive species to a particular location.

A species is native if it is currently living in an area due to natural methods and evolution. For example, the koala is native to Australia, because koalas developed in Australia by themselves, without intervention from humans or other unnatural influences. 

A species is introduced if it is brought to an area where it is not naturally occurring or native. Introduced species can be brought to new areas by humans, either purposefully or accidentally. For example, red foxes were brought to Australia in the 1850s by humans and became an introduced species. Not all introduced species have a negative impact on their new environment; however, introduced species do have the potential to become an invasive species. 

A species is invasive if it is brought to a new area and starts to harm other native species in that environment.