11. The non-transitory computer-readable storage medium of claim 4 , wherein determining the one or more portions of the modified version of the markup document that have not been displayed to the user includes determining a difference between a version of the markup document previously displayed to the user and the modified version of the markup document.
4. A non-transitory computer-readable storage medium storing instructions that, when executed by at least one processor, cause a computing device to: upon receiving a request from a user to view a markup document, access user information to determine portions of the markup document that were previously displayed to the user; based at least in part on the accessed user information, determine one or more portions of a modified version of the markup document that have not been displayed to the user; accessing user activity tracking information to determine portions of the markup document that were previously displayed to the user; based on the one or more portions of the modified version of the markup document that have not been displayed to the user and the user activity tracking information, determining portions of a current version of the markup document that have not previously been displayed to the user; providing the markup document for display to the user at a client system, content of the markup document being modified to include one or more intra-page bookmarks, such that the portions of the modified version of the markup document that have not previously been displayed to the user are distinguished from the portion that was previously displayed in a manner enabling the user to locate and view the portions that have not previously displayed to the user; enabling the user to manually insert one or more intra-page bookmarks in the markup document allowing the user to start at a desired location after closing the markup document; and enabling the user to selectively choose to display the intra-page bookmarks.