Remember input html form

Supposingly I’m using the wrong keywords in google but I can’t find an answer anywhere.

I’ve got some basic html-forms, which are checked in php form:

  • validity,
  • emptyniss

If error then error.html is shown. No problem here. But if you go back the html-form is emptied.

How do you create it that it shows the not filled in inputfield? or at least it remembers the filled in form and empties the bad one?