Html::fillinform automatically inserts data from a previous html form into the html input, textarea, radio buttons, checkboxes and select tags. it is a subclass of html::parser and uses it to parse the html and insert the values into the form tags.

one useful application is after a user submits an html form without filling out a required field. html::fillinform can be used to redisplay the html form with all the form elements containing the submitted info.