Copyscape’s primary use is to detect online plagiarism, to help web users protect their content against copyright infringements. However, you can also use this tool to check if some of the content on your website has actually been plagiarized from other websites. Not everyone is good at creating web content…  If you get inspired by already existing web content, ensure you don’t fall into plagiarism. Publish your content and do a search to check if the webpage relates to other already existing webpages. Then change or rephrase your content if necessary. Your website would thus get better chances to be rewarded by search engines for providing unique content, and of course you would avoid all possible legal issues. Content matters a lot to search engines.

Copyscape is free to use, until a certain amount of searches for a website is made. You then have to become a premium member, unless you don’t mind waiting for a month before you can do free searches again. If your website has several domain names, you may use different web addresses to avoid the waiting time…