Hi friends lets share our definition about Authority Sites i.e what exactly is authority sites and how it plays role in SEO.
Authority site, the dream of every SEO professional. It basically means that your web content are so much relevant to the keyword that Google is asking people to follow the website for more niche information. It can happens if you are having a niche and relevant content, or people typing the keyword and just for entering your website while neglecting others.
It really depends on how you defined "Authority sites". Some people refer it to high ranking sites which Google recognize it on the SERPs. Some refers to site which has at least 1,000 indexed pages with PR3. Some refers to site which with .edu and .gov sites. Some also refers to site with at least 100,000 sites with PR5.
for me an authority site is classed as a website such as about.com that everyone uses to link to when sharing information or articles. Like there are many articles out there about many topics but there are only a handful that people will treat as trusted and the source of information, i believe this goes beyond just .gov .edu websites.
website authority is a by-product of multiple factors (trust rank, relevance and endorsement from websites who have earned a position of authority from search engines). in layman's terms, it is a popular site that people's frequent that gets linked to on the basis of its merit, or that others willingly refer to when the topic of that site comes into play. an authority site does not even have to necessarily have Page Rank to be considered an authority in search engines, but rather it is about achieving harmony with various facets of on-page and off-page optimization that produce this "effect". essentially if your pages provide useful content (and people notice) then every word on every page can potentially can become a keyword and placate relevance for your entire domain when searches are conducted for the main keywords on those pages. i'm sorry if it's not completed. thanks
I would also think that trust, usage, history and other things. For example, CNN would be an authority site on News, Twitter on microblogging, but in essence, it doesn't have to be on a subject. Facebook is an authority site on social networking obviously. Whether we agreee or not, DMOZ is an authority site to Google for Directory. I don't think Google would list the authority sites if you asked, but this is probably one of the areas where a high page rank may play a role in determining Google's interpretation of what an authority site actually is.