How to add input forms in emails?

Question

My friend just sent me an email that embedded html form inputs (textboxes and checkboxes).
How does this work?
I tried typing plain html into the email, but it just sent as plain text.

We both have gmail accounts.
I could not find this feature under gmail lab.

Answer 1

In google documents you can create a form. One of the options in the form is to email this to somebody. If you send it to a gmail address it will show the form in the email.

However most mail clients only support a limited set of html tags, so chances are that outside of gmail they'll have to use the "If you have trouble viewing or submitting this form" link that it includes.