Outline is a note-taking application that features a unique design, intuitive hierarchy, and free placement of notes like a paper notebook, support for various types of content (text, images, inks, tags, Web content, etc.), synchronization options, and Microsoft OneNote compatibility. Outline's hierarchy resembles that of a real notebook: there are notebooks for general subjects, section tabs for specific topics, and pages for actual notes. For more complex notebook structures, additional section groups can be created within a notebook. There are no limitations on the number of notebooks, section groups, section tabs and pages.