Filling text means breaking it up into lines that fit a specified width. Emacs does filling in two ways. In Auto Fill mode, inserting text with self-inserting characters also automatically fills it. There are also explicit fill commands that you can use when editing text.
|• Auto Fill||Auto Fill mode breaks long lines automatically.|
|• Fill Commands||Commands to refill paragraphs and center lines.|
|• Fill Prefix||Filling paragraphs that are indented or in a comment, etc.|
|• Adaptive Fill||How Emacs can determine the fill prefix automatically.|