'' a field on Manage display I'm using D7.

If you set a field &lt;Hidden&gt; on 'Manage display', and, unless you display it by views or something, you cannot see it anywhere on the site, right?

They say...


  Format 
  The format column contains the options to show the field value
  in different formats. Hidden is the global value which is present in
  all the format option list, if you choose hidden then it will hide the
  whole field from showing on the content page.
  
  https://www.drupal.org/docs/7/nodes-content-types-and-fields/specify-how-fields-are-displayed


I understand it hides a field from View mode. But, you can also hide it if you don't try to do by using those modules, which are designed to output fields, like Views, right? Or, is there still any possibility that users can see the hidden field even if those modules are not used?

I'm sorry if this is a very basic question. But, I wanted to make sure what 'hidden' field means.

Thank you.
If you use (Manage display) format: hidden (not label: hidden), the field will not show for this display for this content type. The field could still show in another display (like for teasers). So you will need to set the field format to hidden for all displays. 

It is still possible to make a view with the Views module that displays the field. It depends on how you set up the view. If you set up a view of teasers, the standard teaser display is used (and the field is hidden according to the display settings). If you make a view of fields, you just have to avoid picking the "secret field".

If this is an existing Drupal site where this content type and field is a part of many different views and/or other modules, you will need to test this out. Also if the field is searchable or hardcoded in some template.