Improv theater is like playing pretend with your friends, but on a stage in front of people. Imagine you have to perform a story that nobody planned ahead of time, you just make it up as you go!
You and the other actors start by asking the audience for a suggestion, like a place or an object. Then, you use your imagination to create a story on the spot using the suggestion, and you have to make it funny or entertaining for the audience.
For example, if the audience suggests a spaceship, you might pretend to be astronauts who are lost in space and have to find their way home. Or, if they suggest a dog, you might pretend to be a dog and have to do tricks for your owner.
The most important thing in improv is listening to the other actors and going along with what they say, even if it's not what you planned. This makes the story funnier and more interesting for everyone watching.
In summary, improv theater is like making up a story with your friends on stage without planning it beforehand, and it's all about listening and playing along with each other.