Reading is rarely passive. Now you can mark up a source the way you would a printed paper — and it all stays with the source.
Highlight in colour
Select text in a PDF and highlight it in one of four colours. Your highlights stay exactly where you put them, even as you zoom, and they're waiting for you the next time you open the source.
Add a note to a passage
Attach a note to anything you highlight — a thought, a counter-argument, a "use this in the intro." A small marker shows where your notes are; click it to read, edit, or delete.
Draw with a pen
On a tablet, annotate with your stylus — circle a figure, underline a result, scribble in the margin. It works with a mouse too. There's a colour picker, a few pen widths, and an eraser.
Everything in one place
A new annotations panel lists every highlight, note, and drawing, grouped by page. Click any of them to jump straight to it.