19. A method, comprising: receiving, by one or more computing devices, an image of a portion of a document that was captured by a first user using a camera, wherein the image includes text; identifying, by the one or more computing devices, an electronic document that includes the text; receiving, by the one or more computing devices, a request for a change notification related to content of the electronic document; after receiving the request, determining, by the one or more computing devices, that the portion of the electronic document was modified; and providing, by the one or more computing devices and to the first user, the change notification in response to determining that the portion of the document was modified, the change notification including data that present information informing the first user that the document captured using the camera is not a most recent version of the document together with information identifying, to the first user, a second user that is currently reading the most recent version of the document.
19. A method, comprising: receiving, by one or more computing devices, an image of a portion of a document that was captured by a first user using a camera, wherein the image includes text; identifying, by the one or more computing devices, an electronic document that includes the text; receiving, by the one or more computing devices, a request for a change notification related to content of the electronic document; after receiving the request, determining, by the one or more computing devices, that the portion of the electronic document was modified; and providing, by the one or more computing devices and to the first user, the change notification in response to determining that the portion of the document was modified, the change notification including data that present information informing the first user that the document captured using the camera is not a most recent version of the document together with information identifying, to the first user, a second user that is currently reading the most recent version of the document. 20. The method of claim 19 , wherein the electronic document is a first version of the electronic document, wherein determining that the portion of the electronic document was modified includes identifying a second version of the electronic document that differs from the first version, and wherein providing the change notification includes providing a notification of the second version of the electronic document.