Topicality factors alone aren’t enough to rank, and the introduction of authority factors is what separated Google from other search engines at the time, and allowed Google to gain market dominance. Let’s take our “volcano sledding” example:
170,000 results for “volcano sledding”! All of them are topically relevant to some degree, so which one should rank first?
For most search queries there are hundreds of thousands, if not millions, of pages on the web that are topically relevant. There are thousands that are highly topically relevant. Authority signals are how Google decides which of the topically relevant pages to rank first.
Authority signals are almost entirely based around links. The idea is that the topically relevant page that the most sites link to is probably the best page on the web for that topic. Of course it’s not just about the number of sites, but how authoritative those sites are as well: Google cares a lot more about a link from CNN than it does a link from your college roommate’s blog.
As search engines have grown more sophisticated, they have become more nuanced in how they understand different aspects of links, and today there is a whole host of different aspects of links that count as authority signals. Major authority signals are
- PageRank of linking pages: or the raw link juice, Understanding PageRank is important for SEOs. You can think of it as a measure of the raw numerical authority that flows from every single link into your site.
- Number of linking domains: the more sites that link to your page, the better. The raw number of linking domains is the single largest ranking factor in SEO. One link from 10 sites carries far more authority than 10 links from one site. Some people dive deeper, and look at the diversity of the IP address C-blocks of linking sites. You do not need to worry about this — this is only a concern for people doing blackhat tactics who artificially create huge numbers of links from fake site networks.
- Position of link: a link in the footer of a site counts less than a link in the header, and a link within the actual unique content area of a page is better than either. Similarly a link toward the top of the content is better than a link down at the bottom.
- Relevance of linking site: a link from a page about a similar topic is better than a link from an unrelated page. So if you’re trying to rank a page for the term “artisan snowflakes,” a link from a page also about snowflakes is more valuable than a link from a page about sports scores, or a link from your little sister’s blog. In fact, links from completely unrelated pages may not be counted at all (they usually are though, but only a wee little bit).
- Rel=nofollow: this is HTML code that can be placed on a link that causes the link to pass essentially no SEO value. This is typically used on all blog comments, social media sites and many forums.
- Link frequency: in more competitive markets, the frequency or velocity of links also matters. If one site is getting a new link every other day, that is a strong signal when compared to a site with more links, but that hasn’t gotten a link in the past two years. For lower competition terms, frequency doesn’t matter much.