Backlinks play a big role in SEO: having many good backlinks makes search engines trust your website, so they tend to give your website higher rankings. But not all backlinks are “good”.
First of all, what is a backlink? It is basically your website’s link on other external websites.
Many backlinks signalize to a search engine that your content is trustworthy, so your website is more likely to see higher rankings and appear in search results. Earning those links is link building.
But there are some backlinks that you don’t want to have, and these are toxic backlinks. Essentially, they are low-quality links that violate search engine’s guidelines. Usually they are posted automatically on spammy websites without any editing whatsoever. They aren’t only not helping, but they can also possibly harm.
So, what exactly is a toxic backlink? Generally speaking, it is a link posted on an untrusted domain. A search engine may suspect a backlink to be toxic, if text to HTML ratio is lower than average on the page your link was posted, and if the page contains text similar to many other websites (as if it was a part of a link scheme).
It is no joke since search engines tend to lower rankings or remove links to a website as a sanction. Google, for example, besides automatic algorithms, now has humans reviewing backlinks. If a link or a page where it’s posted is reported as spam or algorithm finds it suspicious, or Google puts special attention on your niche, then there is a risk of seeing penalties.
You can see manual penalties in Google Search Console; just check the Manual Actions section.
If you found a harmful link, you can ask the website it is on to remove it. If you received a manual penalty, you can apply for a reconsideration. If you can’t or don’t want to contact the website who posted your link, you should consider using Google’s Disavow Links feature. The information on how to do that is available here. But use this tool carefully because it can potentially affect your stats, if used incorrectly.
So, as you can see, SEO is not only about building as many links as possible, but also about controlling their quality and whether or not they correspond with Google’s rules and guidelines, and also checking them regularly. Thankfully, there are tools that make these processes easy.