Time dilation is a concept from Einstein's theory of relativity that describes how time can pass at different rates for observers in different situations. When an object moves at a significant fraction of the speed of light, time appears to slow down for that object compared to a stationary observer. This means that a clock on a fast-moving spaceship would tick more slowly than a clock on Earth. Additionally, time dilation occurs in strong gravitational fields, such as near a black hole. In these areas, time moves slower compared to regions with weaker gravity. This effect has been confirmed through experiments, such as observing atomic clocks on airplanes and satellites.