What is the input whose type is hidden used for?

Question

Html input=hidden

Answer 1

It prevents user from manipulating its data (hidden), it's mainly controlled by JS and usually holds secret keys……

Answer 2

This info is written before the "onsubmit" event call of forms and gets cleared immediately after it.......

Answer 3

it is used by many to catch rebot submissions

Answer 4

But when some inspects the elements of a Web page, most of the information can be seen