Your imagination is the ability that you have to form pictures or ideas in your mind of things that are new and exciting, or things that you have not experienced.

Your imagination is the part of your mind which allows you to form pictures or ideas of things that do not necessarily exist in real life.

If you say that someone or something captured your imagination, you mean that you thought they were interesting or exciting when you saw them or heard them for the first time.

If you say that something stretches your imagination, you mean that it is good because it makes you think about things that you had not thought about before.