One of the common requirements I run into when it comes to app forms of any kind is Cascading Dropdowns. So since I'm sure we'll all need them at one time or another, let's run through the steps to create them in PowerApps.
This will be demonstrated on a Change Request app form that collects very basic information about change requests. The app will have three fields: Category, Sub-Category, and Answer. The sub-category will depend on the category selected, and the question the user will have to answer will depend on the sub-category selected.