1. A method for authoring a document at a first computing device, the method comprising: allowing a first unit of data of the document to be edited by a first user; when the first unit of data is edited, providing a first annotation on the document at the first computing device indicating that the document is being edited by the first user; sending a first update from the first computing device to a second computing device indicating that the first unit of data of the document is being edited; receiving a second update from the second computing device at the first computing device indicating that a second user is editing a second unit of data of the document; providing a second annotation indicating that the second unit of data is being edited by the second user; receiving an indication from the first user to display content updates into the document from the second computing device; and updating, by the first computing device, the document to display the content updates.