Invasive species are non-native organisms introduced to an ecosystem which harm the environment, economy, and human health. They can be plants, animals, or microorganisms, often brought in through human activities like trade or gardening. When invasive species take hold in a new environment, they compete with native species for resources, leading to a decline in native populations and even extinctions.

They can damage ecosystems by growing rapidly, blocking sunlight, altering soil, and spreading diseases. Invasive species also impact communities by damaging crops, disrupting food chains, and posing health risks. Preventing their introduction and spread is crucial through measures like biosecurity, trade regulation, and public education.