Alien species, also known as invasive species, are organisms that are introduced to a new environment where they do not naturally occur. These species can come from different regions or countries and may be brought in accidentally or intentionally. Once established, they can disrupt local ecosystems, outcompete native species for resources, and alter habitats. The impact of alien species can be significant, leading to declines in biodiversity and changes in ecosystem functions. Examples of alien species include the Burmese python in the Florida Everglades and the zebra mussel in the Great Lakes. Managing these species is crucial to protect native wildlife and maintain ecological balance.