5. A computer-readable storage medium storing computer-executable instructions that, when executed by a computer, cause the computer to: display a page of an electronic document on a display device using a document browser that permits a user to move forward and backward among a plurality of document pages; detect a selection of an annotation mode that permits the user to annotate a currently displayed document page, wherein at least an ink annotation mode, a highlight annotation mode, and an eraser annotation mode are provided as options from which the annotation mode is selected; receive annotation stroke input from a user input device, the annotation stroke input indicating movement associated with the user input device for a continuous distance about a stroke location on the currently displayed document page; store annotation stroke data based on the received annotation stroke input, said annotation stroke data comprising data corresponding to the stroke location and the movement associated with the user input device, wherein the annotation stroke data is stored in an annotation file associated with the user, the annotation file stored separately from the electronic document; storing annotations made in the highlight annotation mode as a bitmap image; and blending pixels in the annotation file with pixels in the electronic document to cause the computer display device to display the electronic document with annotations, wherein the computer-readable storage medium is not a signal.
5. A computer-readable storage medium storing computer-executable instructions that, when executed by a computer, cause the computer to: display a page of an electronic document on a display device using a document browser that permits a user to move forward and backward among a plurality of document pages; detect a selection of an annotation mode that permits the user to annotate a currently displayed document page, wherein at least an ink annotation mode, a highlight annotation mode, and an eraser annotation mode are provided as options from which the annotation mode is selected; receive annotation stroke input from a user input device, the annotation stroke input indicating movement associated with the user input device for a continuous distance about a stroke location on the currently displayed document page; store annotation stroke data based on the received annotation stroke input, said annotation stroke data comprising data corresponding to the stroke location and the movement associated with the user input device, wherein the annotation stroke data is stored in an annotation file associated with the user, the annotation file stored separately from the electronic document; storing annotations made in the highlight annotation mode as a bitmap image; and blending pixels in the annotation file with pixels in the electronic document to cause the computer display device to display the electronic document with annotations, wherein the computer-readable storage medium is not a signal. 6. The computer-readable storage medium of claim 5 , wherein the user input device comprises a stylus.