With Sitecore 9.0 we have the release of the brand new Experience Forms which is quite different from good old Web Form for Marketers. I had a hands-on experience with this module and performed some investigation on its architecture. The video is a recording of the briefing session I conducted with my team members. Hope you find it useful as well.
Basic Knowledge of Sitecore (any version)
Sitecore 9.0 installed. If you haven’t already done it, you may find these awesome videos from Alen Pelin useful.
WFFM still can be installed on Sitecore 9
Forms main page loads forms from Sitecore Master Index
Forms can be saved as a template for reusability purpose
MVC form is the only option you have (farewell to Web Forms)
There are additional steps to make the form work on the front end. documentation can be found here.
Mongodb is gone and data is stored in separate SQL Server Database