Easy access to the World Wide Web has raised concerns about copyright issues and plagiarism. It is easy to copy someone else's work and submit it as someone's own. This problem has been targeted by many systems, which use very similar approaches. These approaches are compared in this paper and suggestions are made when different strategies are more applicable than others. Some alternative approaches are proposed that perform better than previously presented methods. These previous methods share two common stages: chunking of documents and selection of representative chunks. We study both stages and also propose alternatives that are better in terms of accuracy and space requirement. The applications of these methods are not limited to plagiarism detection but may target other copy-detection problems. We also propose a third stage to be applied in the comparison that uses suffix trees and suffix vectors to identify the overlapping chunks