Imagine the Earth is a ball. The middle part of this ball, or the part that's not too close to the North or South Pole or too close to the Equator, is called the middle latitudes. It's like the middle part of a sandwich, not too much of one thing or another.
People and animals live in the middle latitudes because the weather is not too hot or too cold, and everything they need to survive is available. The middle latitudes have four seasons: spring, summer, fall, and winter.
But, the weather in the middle latitudes can change quickly because it's influenced by different air masses. Sometimes cold air from the North Pole moves in, making it very cold. Other times warm air from the South can travel up and make it hot.
Overall, the middle latitudes are an important part of the Earth where many of us live and get to experience different weather conditions.