What makes a backlink high quality is subjective, and every SEO consultant will have at least a slightly differing opinion on the topic, however, most would agree that a good quality backlink would be comprised of several of the factors listed below, and that a backlink that ticks all of these boxes would be the perfect backlink.
It would be unrealistic to expect all of your backlinks to be perfect, and just because a backlink doesn’t meet all of these criteria it doesn’t make it low quality. If you can get a backlink to your business’s website that ticks at least a few of these boxes then it’s definitely worth having in your site’s link profile.
Search engines want to provide relevance in their search results, and so it’s logical that relevance is a consideration when they evaluate backlinks, which are the primary factor affecting where sites rank in their results. A backlink can be relevant on different levels. Search engines consider the overall relevance of the linking site, the relevance of the specific page with the link on it, and the relevance of the content directly surrounding the link.
It’s logical that a high quality backlink would come from a high quality website, and that a high quality site would also be a very trustworthy site. To determine if a website is trustworthy, search engines use a set of trusted seed sites (for example, Wikipedia, BBC, The Huffington Post, etc.), which they know for sure are high quality and which are difficult to get links from. The fewer the number of links away a site is from one of the seed sites, the higher its TrustRank is, and the higher the quality a link from that site is.
This aspect of backlinks too often gets forgotten about. The original purpose of links, before the time search engines started using them as a factor in their algorithms, was to add value to a page by directing visitors to resources relevant to the topic of that page. Visitors still click these links as often as they did when the internet was first created, and having a link in a prominent position on a highly visited page makes it high quality because, regardless of rankings, it will bring your website a continual stream of targeted visitors.
The quality of a backlink increases if the words that form the clickable text of the link are the same as, or similar to, the words that you’re trying to improve your rankings for. It looks unnatural to have a lot of incoming links made up of exactly the same anchor link text though, so use plenty of variations. If you’re trying to rank your site for ‘mortgage advice’, as well as getting links with ‘mortgage advice’ as the anchor link text, good variations would be ‘advice on mortgages’, ‘professional mortgage advice’ and ‘mortgage guidance’.
In-content backlinks (i.e. backlinks within a block of text) are the most likely to be editorial links, which are exactly the type of links that search engines value most, and if a link is included early on in a piece of content then it’s natural to assume that the author of that content considers it be an important link. Therefore, a backlink within the main content area of a page, and towards the top of that content area, is considered to be more high quality than a link lower down the page or in the sidebar or footer.
PageRank (PR) is the most basic and obvious measure to use when assessing the worth of a backlink – the higher the PR of the page where the link is located, the higher the quality of that link. PR can be a misleading metric though. All webpages start off with a PR of 0 (or n/a to be precise) and the PR of a page can rise and fall over time. Also, the PR value that Google displays for a page is only updated for the general public every 3 or so months, but within the algorithm it’s updated constantly. So, the PR value you see is only an estimate, and could well be a point or 2 off of the true PR.
If a backlink to your business’s website is included on a page that links to high quality sites, especially ones in the same niche as your site, then it indicates to search engines that your site should be put in the same bracket as those high quality sites. If the other links on the page are to low quality sites, then your site won’t necessarily be classed as low quality also, but rather search engines may opt not to include those links as a factor, either positively or negatively, in their ranking calculations.
There’s a strong correlation between higher rankings for a website and the number of unique websites (i.e. different domain names hosted on different IP addresses) linking to that site. All else being equal, it’s preferable to have 10 links from 10 different websites than 100 links from 3 different websites. So, for a new link to your business’s website to be considered high quality, it should be from a website which hasn’t already linked to you.
Link exchanges were widely abused in the past, which resulted in the value of reciprocal links being reduced. Reciprocal links do still have value, and there’s certainly no risk of a penalty being applied as a consequence of them, however, if you’re looking for a backlink of the highest possible quality, then it should come from a website that you’re not also linking to from your own site.
The trust and authority flowing through a page with a backlink to your site on it gets divided up between all of the links on that page, and so the less links there are on a page, the higher the quality of the links on the page, as the the trust and authority passed on is less diluted. It depends on a few factors, but as a rule of thumb, having a link to your site share a page with less than 10 other external links would be considered good.
The more easily you can acquire a backlink, the less value it will likely have. The chances are that if you can get it a couple of minutes, or with a couple of clicks, then thousands of people will have done it before you and thousands more will do it after you – including your competitors if they take the time to review your site’s backlink profile. If a competitor replicates one of your links then the value of that link to you has been neutralised in your head-to-head SEO contest with that particular competitor.
Paid links can, and often do, improve rankings, however, they can’t be classed as high quality backlinks because of the risk they carry. Search engines explicitly say that purchasing backlinks for the purpose of improving the rankings of your website contravenes their guidelines, and that websites found to be doing so may be penalised. The payment doesn’t need to be made directly to the website linking to you either, it can be via a 3rd party linking scheme, such as a blog network.