An authority is an accepted source of information. In SEO terms, authority is generally understood to refer to how important Google and other search engines consider a page to be and therefore how competitive that page is in search rankings.
In reality, SEO-related authority is not a single metric that is measured independently but is the result of several factors that play a role in search engine ranking algorithms. These include (but are not limited to):
- Author authority
- Domain Authority
- Links to and from the page
- Social media mentions
- Domain registration information
- Site age
- Usage information (time on site, page views, etc.)