While OS X has offered the ability to sign PDFs since the days of Leopard, Apple has streamlined the process in Yosemite. Where users previously had to open documents in the Preview app to take advantage of the feature, now it’s part of Markup in Mail; just click the new “add signature” icon in the pop-up menu and you’ll be able to sign your document, either by using the trackpad or scanning your John Hancock with the camera. (MacLife)