The Forms application enables content editors to create and publish on-line forms. Forms allow you to gather structured data from your site visitors. A typical example can be a Contact Us form or a form in which visitors provide additional about themselves. The information a visitor provides via the form then updates the contact that represents the visitor in the system. This way, visitors can provide email addresses that you can then use to send marketing emails.
Forms are a different concept than alternative forms, which are used as alternative representations of existing forms and tables.