Mastering the secrets of search engine optimisation (SEO) is a constant battle. The days when high keyword density was enough to get your website a high ranking on Google are long gone. The search engine giant is constantly updating its (proprietary) search algorithms, which means that metrics are constantly changing. They are also better than ever at detecting and stopping so-called black-hat SEO tactics. In other words, it's harder than ever to achieve a high search rank and avoid being penalised by Google. SEO is not for the faint-hearted.
The good news is that there are still things you can do to build quality backlinks and improve your SEO. One very effective example is the use of private blog networks (PBNs). This strategy is the "secret sauce" that many top agencies and SEO gurus use to dominate the search engines.

So what is a private blog network?

Firstly, let's talk about what a PBN is. Simply put, it's a collection of websites owned by a single company or person. It is used as a way to place outbound links for customers. If you've ever looked into off-site SEO, you know that finding quality backlinks is hard work. Google frowns upon buying links, and webmasters who do so can be subject to significant penalties if caught.
The advantage of a PBN is that, if you do it right, you can build up a collection of high-quality links from reputable websites. Of course, there are also some risks. Here is a brief overview of the pros and cons of using PBNs:

Take the time to find expired domain names for websites that already have links
Do not use websites with spam links, such as links to pornography
Keep the websites in your network active by regularly publishing new content
Don't expect Google to overlook inactive websites that only add new links and nothing else
Build a network of related websites that contain content relevant to your niche
Don't waste your time on websites with low authority or trustworthiness

In other words, PBNs carry many of the same risks and rewards as other SEO techniques. If you build a PBN and take the time to do it right, it can end up boosting your Google rank and providing a valuable resource for people interested in your niche. Cutting corners and neglecting the details can lead to a Google penalty - and if that penalty is severe enough, it can put you out of business.

How to set up a PBN

Now that you know what PBNs are and why they can be so valuable for your search engine optimisation, let's talk about the steps required to build a PBN.

Find expired domain names, preferably those that are relevant to your niche or industry. There are many different reasons why domain names expire. Sometimes domain owners forget about them, miss a renewal deadline or have simply moved on to other products and websites. Expired domain names are easy to find. On websites like ExpiredDomains or FreshDrop you can search for domain names that you like.
Research each potential domain name to determine its value as part of a PBN. One of the tools I like to use is Majestic SEOwhich allows you to check various key metrics to determine whether a website is worthwhile. We'll talk more about which metrics to evaluate in a minute.
Once you have identified viable domain names, register the selected domain names and make each one an active website with fresh and relevant content. As I mentioned earlier, it's very important that every page in your PBN is active. Stagnant sites with outdated content are much more likely to be rated negatively by Google than active sites.
Add links and make sure that each link you place is relevant and adds value to the website.

When evaluating expired domain names, there are some important criteria you should check before registering the name. Some of the things I like to look at are:

Page Authority. Page authority is a formula developed by Moz that allows you to estimate where a website will rank in Google's search hierarchy. Changes to Google's algorithms often mean changes to your Page Authority. In general, you should look for websites whose pages have a page authority of 25 or more.
Domain authority. Like page authority, domain authority is also a ranking that indicates how a domain name performs in searches. However, instead of looking at individual pages, the entire domain name is considered. When looking for viable domain names for your PBN, look for domains with an authority of 20 or more.
Trust Flow. Trust Flow is a metric developed by Majestic SEO that determines the trustworthiness of a website based on the pages it links to. Look for domain names that have a Trust Flow score of at least 15.
No anchor spam. This is not a fixed metric, but it is important. It is important to avoid websites that contain anchor spam such as links to porn and other dodgy content.
Clean archive history. Check every domain name that you find on org to ensure that it is free of 301 redirects and has not been abused in the past.

The reason you check your domain names this way is because you don't want to buy a domain name only to find that you've inherited problems that make the site unusable. There is no point in investing money to reserve a domain name that has been tainted by bad links, spam or black hat SEO practices.

The quintessence

The bottom line is that building a private blog network can be a very effective way to improve your website's Google rankings, but it's extremely important to get it right if you want to reap the benefits and not jeopardise your website by doing it wrong. For this reason, it may be best to hire an agency to do the work for you.
The SEO experts who build PBNs professionally know the pitfalls and have the resources they need to identify the right domains, as well as the experience to eliminate problematic websites. A carefully constructed PBN is a worthwhile investment for any business looking to improve its Google ranking.