There are three potential sources of user interaction for your app's workflows. Each allows users to intereact with your app and for your app to respond accordingly to their input.
Forms are a straight-forward way to collect user input and pass it onto to other parts of your workflow. Their interactivity is one way - users interact with a static form. You cannot update the form itself based on user input.
Forms are created with the OpenForm Slack function.
➡️ Read Creating a form for instructions.
Interactive messages are messages containing interactive Block Kit elements. Send interactive messages to users to collect dynamic input from users, and use that input to kick off other parts of your workflows.
Interactive messages are created with Block Kit, and have their interactions reflected by Block Kit action events.
➡️ Read Creating an interactive message for instructions.
Interactive modals are modals containing interactive Block Kit elements. Modals have a larger catalog of available interactive Block Kit elements than messages. They can also be updated to reflect the user's inputs as they interact with the modal.
Interactive modals are created with Block Kit, and can be opened as a result of a Block Kit interaction or a trigger. They are updated by View events.
➡️ Read Creating an interactive modal for instructions.