A simile is a figure of speech that compares two different things using the words "like" or "as." For example, saying "Her smile is like the sun" helps us understand how bright and warm her smile is by comparing it to the sun. Similes make descriptions more vivid and relatable, allowing readers to visualize the comparison easily. Writers often use similes in poetry and storytelling to create strong imagery. When someone says, "He runs as fast as a cheetah," they emphasize the speed of the person by comparing it to the fastest land animal, the cheetah. This technique adds depth and creativity to language, making it more engaging.