Social Signals are what a search engine sees as your total number of likes, shares and overall popularity of website/ page on social media.

Social media and its signals are now very important in determining the overall SEO score of a website.

A web index’s main job is to give high-calibre, important weblinks to clients. Web crawlers check quality in huge part by how often a URL is seen all through the web, and as more web communication has moved to social media, Google, Bing and other search engines have incorporated social signals as a sign of relevance and popularity.