There are different types of animals, all of them very important for nature. For example, we fear the sharks and find them dangerous, whereas they naturally keep sea water clean and filter it. Animals refer to fauna and they are equally important for nature and people. There are two types of animals so far: domestic and wild. Domestic animals, which we often call pets are very dear to people. However, wild animals can be rather dangerous for human beings. Domestic animals can easily live next to people, whereas wild animals’ habitat is mainly in forests, jungles and oceans. At the moment, there are hundreds of animal species which are becoming extinct due to people’s anti-natural actions. These are mainly wild animals. There is a high chance that following generations might see some animals only on pictures because by that time they will have died out. Fortunately, there are still lots of monkeys, zebras, lions, wolves, giraffes in the wild. Domestic animals play a very important role in people’s lives. While people take care of them, they give something useful in return. For example, chickens give eggs, cows give milk, dogs protect people, cats catch mice, sheep can give fur etc. There has been a recent increase of homeless animals, especially of cats and dogs. From one hand, homeless animals can be rather dangerous for people, from the other hand, people often try to help them by taking them home, feeding them and simply taking care. There is also another type of animal classification. We distinguish following main groups: mammals, insects, birds, fish and reptiles. Mammals are animals who feed their kids on milk, among them cows, dogs, dolphins, kangaroos, and many others. Insects are small creatures with numerous legs and usually wings. Birds are all animals with feathers. Fish live under water and can swim. Reptiles are animals without wings which lay eggs, among them snakes, crocodiles, lizards and some others. All these groups of animals contain several rather dangerous species. Nevertheless, people should try treating them well, not taking actions which cause their extinction.