Bookmark a place in your document with {{%m}} or Tools > Insert Marker (⌘ Control + M).
Quickly jump back to it with Tools > Go to Next Marker or ⌘ Control + ⌥ Option + M.
You can set as many markers as you wish. Use them to jump back and forth between sections, or set them at the top of each Chapter.
Markers can also be named. Just add a colon and a label: {{%m:label}}
Named markers show up in the Navigator sidebar and can be used to help you keep track of elements in your outline, like beats in a story thread or appearances of a character. Think of them as tags in your document.