With a note open, click the Show Note Inspector button at the right end of the toolbar (the icon of a window with a right-hand panel). Click it again, press Esc, or use the close button in the panel's header to put it away.

Other ways in, each landing on a particular tab:

• ⋯ → Note Properties opens Properties.
• ⋯ → Sources & Files → Attachments opens Navigator; ⋯ → Sources & Files → References opens References (only when the note cites something).
• Press ⌘K and run History to open the note's timeline.

The Inspector has four tabs: Properties, Navigator, History and References. It reopens on the tab you used last, and it stays open as you move between notes. Opening it closes the Assistant panel if that's open, since both use the right side of the window. Above the tabs, a small line gives the note's length, such as "1,240 words · 6 min read".

Properties are the key: value lines in a block between --- markers at the top of a Markdown file, often called frontmatter. Other Markdown apps read the same block. The Properties tab shows the ones your note has and lets you change them:

• Type and Status have a Change button with a list to pick from (types such as note, meeting, project, decision; statuses such as draft, active, evergreen, archived), or Custom... for your own word.
• Tags has an Edit button. Add a tag in the field, click a tag to remove it, or pick from the suggestions.
• Owner, Project and Summary are plain text boxes.
• Created, Updated and Path are shown for reference. Created and Updated come from the properties if the note has them, otherwise from the file.
• Anything else is under Custom fields. Header picks a control from the value: a date gets a calendar, true/false gets a checkbox, and so on. Hover a field and click the minus button to remove it.

To add one, open Add property. Click a suggestion such as Project or Owner, or type a Property name and Value and click Add. Names must be plain YAML keys, such as project or source_url. If the note has no frontmatter yet, Header creates the block. Clearing a value removes that line.

At the bottom are Copy note link, Reveal in Finder and Open in Source, which shows the raw Markdown, frontmatter included.

The Navigator tab has three sections, Outline, Links and Attachments. Each folds away, and Header remembers which you keep open.

Outline lists the note's headings, indented by level, with the one you're in highlighted. Click a heading to jump to it. The arrows beside a heading fold its sub-headings in the outline only; the note itself doesn't change. With no headings you'll see "No headings yet".

Links has three lists:

• Backlinks: notes that link to this one with [[…]].
• Outgoing links: notes this one links to.
• Unlinked mentions: notes that contain this note's title as plain words but don't link to it, each with the line where it appears. The match ignores capitals but needs whole words, and titles shorter than three characters are skipped.

Click any entry to open that note, or the board, if the link comes from a board. Unlinked mentions are a reading list, not a fixer: to turn one into a link, open that note and add the [[link]] yourself.

Attachments lists the files the note embeds, such as ![[floor-plan.pdf]] or a local image. Click one to open it in its usual app, or right-click for Open and Reveal in Finder. A file that has gone missing shows an orange dashed icon.

If you cite sources from your Research library, the References tab lists them with author and year. Click one to jump to where it's cited, or right-click for Jump to citation, Open PDF and Reveal PDF in Finder. A citation Header can't match shows as @key with a Resolve… button. Two buttons sit at the bottom: Export cited…, which exports just the sources this note cites, and Research library. Citations themselves are covered in Research & the Reading Room.