If you didn't create or think of something first, you should be sure to seek licensure or properly credit the bearer of the Intellectual Property rights. We are all somewhat familiar with plagiarism, copyright infringement, trademark violations, patent infringement, and yes, even digital copyright infringement. Though this list is not comprehensive, you get the point. If you have questions about the origin or ownership of something you plan to use, make sure that it's not aleady another's protected work. Even ideas are protected so take care that you don't use something without properly licensing use, crediting the true source, or violating another's legal protections.