Many students end their papers by simply summarizing what has come before. A summary of what the reader has just read is important to the conclusion - particularly if your argument has been complicated or has covered a lot of ground. But a good conclusion will do more. Just as the introduction sought to place the paper in the larger, ongoing conversation about the topic, so should the conclusion insist on returning the reader to that ongoing conversation, but with the feeling that they have learned something more. You don't want your reader to finish your paper and say, "So what?" Admittedly, writing a conclusion isn't easy to do.