A summary is a breif explanation/sum up of what you have talked about or what ever the topic was. It is used to wrap up everything you have explained. It is better to use summary's so that we can say the main idea in less words and so people can read it quicker and get the idea of that topic.
Okay, Ok, and O.K. are all acceptable spelling of "ok"
Cause or become is what the suffix -fy means.
