According to the Oxford Dictionary, "authority" is:
"The power to influence others, especially because of one's commanding manner or one's recognized knowledge about something."
In Search Engine Optimization (SEO), your goal is to be the authority in your industry on a certain topic or topics. You want to be the one supplying expert insight and creating trust with your potential clients. As said by New Media expert, Chris Garrett, over at chrisg.com:
"Authority in a search context takes into account all the elements of a site then determines a grading on the spectrum from completely authoritative through to no authority at all. The more authoritative and trusted your site, the better you will rank."
According to Search Engine Land, "trust plays a big role in whether a site will succeed or fail from a search perspective". SEO is a big deal and it is not simple. There is no instruction book. It is constantly changing, and search engines such as Google purposefully keep their algorithm a secret so that people can't cheat. With that being the case, much of SEO is educated guessing. There are definite things that can be done to affect SEO because Google has made certain requirements obvious. However, authority is one of those SEO factors that is a gray area.
Every SEO specialist knows that link building is a huge factor in trust, and keyword integration greatly affects authority. However, trust and authority, are separate entities and yet somehow intertwined. Picture a spider's web- that's SEO. Everything is connected, and yet even the professionals are still working to figure out how they are all connected. With Google and other search engines refusing to share their secrets, all SEO specialists can do is research, test theories, do what they know works, and when that stops working (because Google has changed their algorithm) they start the cycle over.
You may be asking, why would I hire someone to do SEO on my site if they are just making educated guesses? Because they are very good at it. As SEO specialists, they:
When you are lost and unsure of where to start on your website, the SEO specialists swoop in to rescue you. The important thing to remember is that the results are not immediate. Gaining authority and trust with search engines takes time and a lot of work, just as with anything else in life.