Domain authority

What it means

Domain authority is an estimate of a website's strength in search engines, calculated by commercial SEO tools, usually on a scale from 0 to 100. It is based mainly on the number and quality of backlinks, meaning how many trustworthy sites link to the site.

Search engines do not use this metric themselves; they have their own internal signals. Domain authority is nonetheless useful for comparing sites and judging how hard it will be to outrank competitors.

It is related to topical authority, which describes not links but how deeply and credibly a site covers a subject. Search engines value the combination of both.

How it works in practice

When planning link building, domain authority helps pick sites worth getting a link from. One link from a respected industry portal is worth more than dozens of directory links.

With low domain authority, it is more realistic to target specific long-tail queries with weak competition and build content and links gradually. Generic terms are held by sites with long histories.

Authority grows slowly as a result of off-page SEO, good content and time. When moving to a new domain it can only be carried over by redirecting old URLs properly.

What to watch out for

Chasing a higher number can lead to buying links, which search engines penalise. The tool's score then rises while real rankings fall.

Different tools calculate authority differently, so values cannot be compared across tools. Watch the trend in one tool and, above all, organic traffic and enquiries.