When every single member of a species dies and none are left alive, then that animal has gone extinct. Extinctions can happen for many reasons but recently people have been a major cause.
Over hunting can led to extinction as can diseases, climate change or habitat loss which is when animal’s homes are destroyed.
In the past, there have been very large extinctions where many species have gone extinct together. This is called an extinction event. One of these events wiped out the dinosaurs.
65 million years ago, all dinosaurs (except birds) went extinct as did many other types of plants and animals. It was at the end of the Cretaceous period and scientists think that it was caused by a big meteor.
A meteor is a big rock that comes from space. When this meteor hit Earth, there was a massive explosion and dust was blown into the sky. Scientists think this dust changed the Earths weather and made it very cold and dark. Animals found it hard to survive and many died. Dinosaurs were just some of the animals that went extinct.