How backlink tools work?

[Yuga]

Backlinks help search engines determine how authoritative and relevant your site is on the keyword or topic for which you rank. Furthermore, backlinks to your website are a signal to search engines that other external websites are endorsing your content.

[julia timpi]

Backlinks help search engines determine how authoritative and relevant your site is on the keyword or topic for which you rank. Furthermore, backlinks to your website are a signal to search engines that other external websites are endorsing your content.

[Lishmalinyjames]

SE Ranking.
Sitechecker. ...
RankActive. ...
Ahrefs. ...
Coupler.io. ...
OpenLinkProfiler. ...
RankSignals. ...
BuzzSumo.

[Kaushik Roy]

They crawl billions of URLs, but their link index is never complete or perfectly fresh. "Domain Rating," "Authority," and similar scores are proprietary estimates, not Google metrics. Use them for link discovery, competitor research, anchor analysis and gap analysis - not as a crystal ball for rankings.