Backlinks
Number
Refers to the total number of external links from other websites pointing to your website. Backlinks are a significant factor in search engine rankings. Quality and relevance of the backlinking sites are crucial. Besides the number of links, you may also look into total number of referring domains, links lost, and links earned.
Formula
Total count of incoming links from external websites.
Example
If 200 different websites link to your content, you have 200 backlinks.