PDF forms are PDF Documents which have interactive elements (checkboxes, text boxes, radio buttons, etc). So you can enter and alter data on them. This makes them very useful for collecting data, placing orders and creating invoices. People have even written games using them! This data can be saved as part of the document or submitted to a server. Here is a fun example of a PDF form
You can see some more example forms on our FormVu sales page.
There are 2 types of PDF form based on 2 different technologies – FDF and XFA. They are very different technically and most PDF viewers do not support XFA. You need to use Adobe LiveCycle to process them (Itext and our FormVu converter can also handle them). Most PDF Viewers do support FDF by default – you do not need any additional software to display them.