Backlinks in search engine optimization (or back-links (UK)) are nothing but the total number of links to a web page or website. In the search engine optimization (SEO) earth, the number of back links is one sign of the popularity or significance of that website or else page (though other procedures, such as PageRank, are probable to be more significant). Outside of SEO, the back links of a webpage may be of important personal, semantic interest or cultural: they specify who is paying interest to that particular page.

In basic link vocabulary, a back link is any link received by web nodes such as web page, website, directory or top rank domain) from a new web node. Back links are also known by various other names such as inbound links, incoming links, inward links and inlinks.