display none is one of the properties of css and is used when switching the display / non-display of the specified element.
For example, it is possible to switch the content displayed for each terminal within the same HTML. Since the elements that cannot be seen with display none can be seen by looking at the source, the displayed content differs between the robot viewing html and the user viewing the browser.
Precautions on SEO when setting
display none By misusing display none, it becomes possible to show text etc. only to search engines so that it cannot be seen by the user. Such text is hidden text and isprohibited by Google’s guidelines, and you may be penalized if you allow it to do so. Even if it is not treated as spam, the contents hidden by display none will not be evaluated by search engines at all or almost never. It’s a good idea to keep important content on the page visible at all times and to use display none for supportive content.
Difference from visibility: hidden
Similar to display none is visibility: hidden.
In the case of display none, the element is regarded as lost and the next element is packed and displayed, while visibility: hidden simply makes it invisible, so the area specified by visibility: hidden is blank. Is displayed as.
Despite these differences, visibility: hidden, like display none, is similar in that it hides elements from the user, so they can be treated as spam when used for malicious SEO purposes.