Anything related to the Web Forms For Marketers module.
Web Forms for Marketers (WFFM) is Sitecore's free module that allows marketers to create and publish simple forms, usually without a developer's help. It provides an easy wizard interface to define form fields with pre-set types, validation rules and save actions that determine what happens on form submission.
https://doc.sitecore.net/web_forms_for_marketers
https://doc.sitecore.net/web_forms_for_marketers/82/setting_up_web_forms
