People change the Earth around them. They cut down trees. They build homes. They build roads. They build factories. All of these changes hurt the animals and plants that live in that place.
Living things get everything they need from their habitat. They get food. They get water. They get shelter. They get space to live. If the habitat changes, the living thing might not be able to live there anymore.
Many animals live in forests. What do you think happens when the trees are cut down? People build homes or factories there. The animals have no place to live. Some living things can find new homes when humans take over or change their habitats. Other living things can't find new homes. Those living things die.