The World Wide Web is made up of two things: content and links. Whenever web users navigate a site, most likely they'd skim through pages of content by clicking internal links. However, for SEO purposes, links from other sites, which are called "inbound links" or "incoming links," matter more.
In fact, links are the number one factor that affects your Google Page Rank. And building links is no walk in the park.
Historically, the first search engine named Wandex only analysed the content of websites it crawled without considering the other sites that linked to them. Such algorithm had many drawbacks, including being used by marketers to better rank their sites despite low-quality content.
Today's search engines, like Google and Bing, use specific algorithm to analyse websites based on the external links that point to those sites. Such algorithm is much more objective as it allows other sites to provide "votes of approval" by linking them. These links are also called "backlinks."
Since Google is the number one search engine, it becomes our focus in this article.
In a nutshell, the more and the higher quality the sites that link to a particular site, the more reputable it becomes. This means that a site's Google page rank would elevate after it's linked by several sites with high DA (domain authority) or PA (page authority). And the one with the highest rank would appear at the top of Google search result for a specific keyword.
In this article, let's discuss how Google algorithm works that made PageRank different from other algorithms.
However, please keep in mind that these rules aren't written in stone and search engine algorithms change from time to time. For a history of Google algorithm updates, Search Engine Journal has the complete list.
The Three Principles
1. Links are counted as votes.
Offline, you get acknowledged by the number of votes received. The more votes you receive, the better your position would be. The same thing with links, the more incoming links that point to your site or page, the better.
Why better? Because the higher the rank, the more likely your site or page would show up at the top of Google search result based on a particular keyword. The higher the position is definitely better as most 75 percent of people only browse on the first page.
2. Pages with more inbound links gain more votes, thus are ranked higher. Quantity matters.
The general rule of thumb is: the more inbound links received, the higher the rank on search engine result. However, not all links are equal. Despite quantity matters, quality is more important.
3. Important pages cast more votes. Thus, pages receiving links from important pages become more important as the result. Quality matters more than quantity.
In a nutshell, the more inbound links, the better, but high quality links are much better. In addition, there are additional rules that affect how Google evaluates links. But what constitute "high quality" and "low quality" links? The answer follows.
Favourable Incoming Links
1. The older the domain of incoming link, the better.
This is a general rule. However, if the link from an old domain is of inferior quality, it doesn't matter. The age of the domain only receives a higher score if the comparable sites provide a similar level of quality.
2. The higher the Page Authority of the incoming link, the better.
The higher the Page Authority (PA) score of the inbound links, the more likely your site would receive a high score that determines a prominent place on Google search engine result. PA algorithm predicts how well a page would rank on search engine result pages (SERP). It's similar to Domain Authority (DA) that measures the strength of a domain instead of a page.
3. Incoming links from sites with .gov and .edu extensions carry more weight than sites with other extensions, like .com, .co, .us, and others.
Government and education institutions are known for their strict criteria for linking other sites and pages. They're also possess a very high credibility as non-profit organisations that aren't likely to be paid to post links to other sites.
4. Incoming links from direct competitors carry more weight than from non-competitors.
If your site or page is mentioned by competitors, more likely it has something valuable to them. Thus, search engine algorithm would recognise this as a positive factor.
5. Incoming links from domains with a similar niche also carry more weight than from unrelated niches.
Being linked by other sites within a similar niche is also recognised by search engines as a positive factor that adds weight to page rank score. Such a link is a vote from niche counterparts.
6. Incoming links from "authority" pages give your page a boost, according to Hilltop algorithm.
Hilltop Algorithm recognises them as authorities in the subject link those pages in the niche. "Expert documents" include university sites, library sites, Yahoo!, and DMOZ directories.
7. Incoming links from Wikipedia despite only uses nofollow links.
Wikipedia's powerful brand would give a favourable boost to your page, despite nofollow, as the editors accept only reputable references. Thus, being linked is a privilege.
8. Incoming links from high-quality pages that link your page as a reference receive more credibility.
Like being linked by Wikipedia, receiving incoming links from high-quality pages outside .gov and .edu would be recognised by algorithm that your page is of high value and reputation.
9. The total number of incoming links that link to your site or page would determine the overall ranking.
Again, it's the quality that matters more. However, the number of links received also determine the overall ranking.
10. Links from sites with a high TrustRank score would be considered more important, thus your site receives more trust.
TrustRank is an algorithm designed to analyse the usefulness of web pages and to avoid spam. Eventually, it assists search engines in SERP (Search Engine Results Pages) by having a small sample of seed pages evaluated manually before having the other pages crawled by automated robot software.
11. The longer the word count of a page, the better the rank.
For instance, a page with 2,000 words would rank higher than a short page of 150 words. Longer articles or blog posts are more sticky, which is a term used to refer to web visitors that stay longer, and allows the writer to write more comprehensively.
12. Links from guest blog posts would help your site rank.
Many digital strategists hire professional SEO writers to work as guest bloggers on other sites. However, when there are too many guest articles, it might cause adverse effects.
Unfavourable Incoming Links (Causing Penalties or Ban)
1. An excessive influx of incoming links in a short time may make Google algorithm think that those are paid links.
Such links may come from guest blogging, social media, press releases, and mentions from various sites and blogs. If they all come simultaneously, most likely Google would flag them for potential removal or penalty.
2. High-quantity of incoming links from individual C-class IP addresses.
Google algorithm would provide higher link score if the incoming links have different C-class IP addresses. If it's from the same C-class IPs, most likely they come from sister companies, which would invalidate the linking processes.
3. Links from sites with a poor reputation would make Google algorithm to associate your site with poor sources.
That's how organic Google algorithm recognises them. It's natural that bad associations would only result unfavourably to your site.
4. Links from bookmark sites or low-quality directories would make Google algorithm think your site also belongs to low-quality sites.
You may be tempted to link your site to bookmark sites like Instapaper, Pinboard, Zootoo! and others. Using them would reorganise your papers for convenient retrieving, but Google wouldn't rank it positively.
5. A huge influx of links from unrelated sites may cause Google's manual penalty.
Links from all kinds of sites with no specific pattern may cause penalty from Google. Slapping links on irrelevant sites, particularly free sites, would only make search engine algorithm to detect spamming that results in penalty or ban.
6. Low-quality links from blog comments, forum profiles, and other signature links common in spamming activities may earn your site a manual penalty from Google.
Incoming links from digital signatures, forum profiles, and blog comments may be considered spammy by Google. Thus, having tons of them may as well earn your site unnecessary penalty.
7. Reciprocal links may gradually lower your site rank as Google would consider it as a link scheme.
Link exchanges between site owners of similar or, even, non-competing niches could eventually lower your site rank as Google may consider them a part of forbidden link scheme. Thus, it's always recommended to carefully discern whether it's appropriate to request for link exchanges.
8. Links generated by user content would receive a penalty as a user-generated spam.
Automated links from sites with contents generated by users are likely to be considered spam and receive a penalty.
9. Links from guest blog posts may result in Google algorithm thinking that it's a link scheme, especially when the blogs are too frequent or too many.
Guest blogging on sites with high DA score is always tempting. However, make sure to be selective and not too frequent.
10. Links bought for the sole purpose of link building, which are often found in lower quality blog networks.
Many lower quality blog networks offer posting links to your site with a fee. They're recognised by Google as link building scheme, thus your site risks being penalised.
In conclusion, pay close attention to the quality of your incoming links. Quantity second. As long as you provide high-quality original useful and informative contents, you can have a peace of mind that Google crawler will eventually review them.
At last, do your best to build inbound links organically. Google and other search engines recognise originality and quality.