Herbivores are animals that only eat plants. They are herbivorous animals.
Herbivores (such as deer, elephants, horses) have teeth that are adapted to grind vegetable tissue. Many animals that eat fruit and leaves sometimes eat other parts of plants, for example roots and seeds. Usually, such animals cannot digest meat. But some herbivorous animals will eat eggs and occasionally other animal protein.
The diets of some herbivorous animals change with the seasons. In the temperate zones of the Earth, some seasons are hot and some are cold, so different plants are available at different times of the year.