Sometimes, web spiders or crawlers that index your site can index your site by using a few different URL. This will lead to duplicate contents issue since the spiders will assume that both of the URLs are different pages although they are actually the same.
Canonical URL is actually a tag that is put in the header section that contain the link of the real page. Due to canonical URL tag, spiders could know whether a page is the real URL or just another alternate URL. If the spiders reach a …