Bake form fields and annotations into the page so they can't be edited.
After filling a form or annotating a document, flatten it before sending: every field value, signature, and comment becomes part of the page itself, so nothing can be altered or accidentally lost in another viewer.
It locks in your answers. Recipients see exactly what you wrote and can't edit the fields — and stubborn viewers can't display them incorrectly.
Nothing visible. Interactive behavior goes away; the appearance is preserved exactly.
No — that's its purpose. Keep the original if you'll need to edit the fields again.