Disavow

Disavow is the umbrella term for devaluing backlinks to one’s own website, i.e. “disavowing” them.
Other frequently used terms in this context are e.g. disavow tool and disavow file.

They all have the same goal: to devalue, i.e. disavow, backlinks that could have a bad influence on one’s own website ranking in Google.

As a website owner, you have no way to regulate who links to your website. In addition to the high-quality backlinks that you would like to see in your backlink profile, there are also links with inferior quality or even toxic links that link to your own website.
So that these “bad” backlinks do not negatively influence the ranking of the website, Google has given webmasters the possibility to devalue these links with the Google Disavow Tool.

The first step is the backlink audit. Here you look at all the links pointing to your website and rate them as “good” or “bad”. This way you can identify bad and toxic links (including spam links, links from link lists, Blogspot spam links, etc.).
To create a good data base, you can export your backlinks from multiple data sources, i.e. multiple tools (e.g. SISTRIX, ahrefs, SEMRush, Google Search Console,…).
SEMRush can also give you a first insight into your Toxic Score. Nevertheless, take a look at every link on domain level manually and apart from the tools. This is the only way to really have all backlinks under control.
Afterwards, all these links, which may have a negative influence on your website ranking, can be entered into the disavow file on domain level and uploaded to the Google Search Console at the end.
This is done in a .txt file according to the format: domain:example.de

This way you tell Google that you don’t want these links to rank your website, and Google ignores the links coming from these domains.

You can disavow links at any time, but be careful not to do so too extensively, as this can lead to ranking losses for your website. After all, the links have set signals to your website in advance.
The recommendation is: once a year
Because, previously high-quality links may have become toxic links in the meantime, or new spam links may be added.
Google says that the spam links are recognized and do not influence the rating of your website, but here it is better to “play it safe” and disavow these links.