A Fleeting note is temporary in nature. It may be a short piece of information that needs to go somewhere, or it is a reminder to take action.
Fleeting notes that are not looked at quickly, can lose their meaning out of the context they were created in. When attached to a source such as a book or article, fleeting notes are markers of ideas to convert to Literature notes.
Fleeting notes go into your GTD inbox for processing. They may trigger the creation of a Permanent note or an action to take e.g., buy milk. It is possible upon review that nothing more is required.
A highlight, underline, or note are enough to make a Fleeting note.
Example of a fleeting note from Meditations taken on my Kindle Scribe. The passage reminded me of perception and the way we observe the world we live in limited from the models held in our mind.