Press ⌃⌥F from anywhere on your Mac, even while you're in another app. A small Jump to Note panel opens with a field that searches every Markdown file in every vault. Type two or more letters and click a result to open it in Header. Each result shows the vault, the date and a short excerpt. Hover a result for a preview with Open in Editor, Open Externally (your default Markdown app) and Reveal. Press Esc or click Close to dismiss it.

The same panel is in Window → Jump to Note, in Header's menu-bar window, and in ⌘K as Search All Notes. To use different keys, go to Settings → Shortcuts → Global Shortcuts; a shortcut needs at least two modifier keys. ⌃⌥H (Show Header) brings the main window forward.

Press ⌘K while Header is in front. The box says "Run a command or jump to a note…". As you type, one list fills with matching notes, boards and commands, each marked Note or Command. You don't need whole words: the letters only have to appear in order, so jptr finds Japan Trip. Use ↑ ↓ to move, Return to open, and Esc to close.

Commands worth knowing: New Note, Open Graph, Open Tags, History (the open note's timeline), and Search All Notes, which opens Jump to Note.

Write a tag anywhere in a note as #tag: at the start of a line or after a space, starting with a letter A–Z, then using letters A–Z, numbers, _, - or /. #reading-list and #client/acme both work. Capitals don't matter, so #Travel and #travel are the same tag. Tags in the note's tags: property count too. Typing # in the editor suggests tags you already use.

The Tags browser lists every tag with the number of notes that use it. Filter the list, sort it by Most Used or A–Z, and click a tag to see its notes and a Related row of tags that often appear with it. Click a note to open it. To go back, press Esc or click the close button (Return to Notes).

In a note, hover a tag to see how many notes use it and the first few of them, with See all in Tags →. ⌘-click a tag to open it in the Tags browser. Header has no command to rename or merge tags; change them in the notes themselves.

Star the notes you come back to every week, say a project hub or this term's reading list. Right-click a note and choose Star Note, or press ⇧⌘B (View → Toggle Starred) for the open note. They collect under Library → Starred, which shows a count. Stars are kept in a small file in the vault's hidden .header folder, not inside your notes, so starring doesn't change a note's text.

For folders, right-click one and choose Pin to Sidebar. It appears under Pinned with its note count. See Your vault & the window.

Type [[ in a note. Header lists notes you opened recently; keep typing to search every note by title or alias, then pick one. If nothing matches exactly, the list offers ＋ Create note, which makes that note next to the current one without leaving where you are. Other forms work too: [[Japan Trip|the trip]] shows different text, [[Japan Trip#Budget]] goes to a heading, and ![[Japan Trip]] shows the other note inside this one.

Click a link to follow it, or hover for a preview. If the note doesn't exist yet, Header asks whether to create it.

To let a note answer to more than one name, give it an aliases: property. With aliases: JP trip in Japan Trip's properties, [[JP trip]] opens it. For several, list them one per line under aliases:. When you rename a note, Header finds the links to it and shows the changes in a review sheet, Update links to "…". Untick any you want to leave, then click Apply … changes. Each edited note is saved to History first.

More on links and embeds is in Writing & the editor.

When Packing list links to [[Japan Trip]], Japan Trip gets a backlink from Packing list. Open the Note Inspector's Navigator tab to see a note's Backlinks, its Outgoing links, and Unlinked mentions: notes that name it without linking. Link a handful of trip notes to Japan Trip and its backlinks become a ready-made index of the trip.