Atmospheric drag is the resistance an object experiences when moving through the atmosphere. This force opposes the motion of the object and is influenced by factors such as speed, shape, and the density of the air. For example, a streamlined shape like that of a rocket experiences less drag than a flat surface. As an object travels faster, the atmospheric drag increases, which can affect its speed and trajectory. This is particularly important for satellites and spacecraft re-entering the Earth's atmosphere, as they must overcome this drag to avoid burning up or losing control during descent.