Wufoo is for building web forms. From a simple contact forms to complex, multi-page, logic-controlled mega forms.
Personally, I'm a huge Wufoo user. I have multiple accounts across different organizations. Each organization has multiple users with access to different forms and reports. I've used it for job applications, customer support, selling T-shirts, collecting feedback, lead generation, and more.
Wufoo has collected literally hundreds of thousands of form entries for me, saving me countless hours of dev work. Often those entries are emailed to me and my team, sometimes they are turned into reports to help us understand something better, and always that data is stored right within Wufoo, accessible through APIs and to Wufoo's many integrations with other apps.