These allow the container to ensure that objects are set up and ready to receive information from the form submission.
Fortunately, the default Validation Tracker provided by the Form component is persistent, so you don't normally have to worry about it.
However, for the same reason, the individual fields updated by the components should also be persisted across requests, and this is something you do need to do yourself – generally with the @Persist annotation.
As with other action requests, the result of a form submission (except when using Zones) is to send a redirect to the client, which results in a second request (to re-render the page).
The Validation Tracker must be persisted (generally in the Http Session) across these two requests in order to prevent the loss of validation information.
These allow the Form's container to set up any fields or properties that will be referenced in the form.