Module provides an api to simplifies building multi step forms. FormMultistepBase class provided by the module take care such things like managing steps, placing next, back and submit buttons at the specific steps (no matter how many steps you need to provide) etc. All you have to worry about with this class to build a multi step form is form.

In the module there is an example module that shows how to build an ajax multi step forms with class FormMultistepBase.