A canon URL is the officially designated “master” version a search engine should consider indexing or possibly ranking. Websites usually have many URLs that point to the same content because there are tracking parameters, session IDs, sorting, etc. In this case, webmasters use a canonical tag to signal to search engines which URL should be taken as the “official” one, creating a single one for all other URLs involved within. Consolidation, avoiding penalties due to duplicate content, and improved search rankings are some of the things that can be achieved through the proper use of a canonical URL. This becomes very important for large websites, e-commerce sites, and content-rich sites.