Fundamental to the way we practice aikido are three types of practice, aikido waza or techniques, aikido weapons and aikido randori. The aikido waza teach us the tools for doing aikido, weapons teach us the mindset and help sharpen out movements because of the precision required in aikido and aikido randori or freestyle practice is playtime with friends.
Aikido randori is a chance to let go of the technical aspects of the art and enjoy free for play as your friends attack you in a continuous manner. Many people watching randori (we call it tanninzugake in our school) remark on its beauty and free flowing movements of harmony. At the same time some say that it looks too choreographed. Well they are right aikido randori is choreographed in the sense that there is a gentleman's agreement between the attacker and the defender nage.
Given the job of attacking uke should not try to counter applied technique and the defender should not use lethal techniques. In this way both get to have the joy of continuous practice without injury. The rules can be changed of course and can include padding up to reduce injury, adding multiple opponents (we restrict the number of techniques that can be applied to keep this safe). here is a video of some aikido randori in action