This is an attribute that is added to a robots meta tag. Thanks to it, search engines are informed that the page should not be indexed in their database. Several reasons can be the basis of such a decision, especially when the website is under construction.
However, Google has announced that this method will no longer be supported from the end of August 2019. It will therefore be necessary to find an alternative if you are one of those who use it.
References –
Other SEO Glossary
Robots.txt | Disallow | On-Page SEO | Allow
