1. A computer comprising: a bus; a processor unit connected to the bus; a computer readable storage device connected to the bus; and program code for collaborating, wherein the program code is stored on the computer readable storage device and is configured to be run by the processor unit to: modify a presentation of a document that includes a plurality of portions by making each portion of the document selectable by a user; identify a context of a user-selected portion of the document in response to receiving a selection by the user of a portion of the document; identify a set of collaboration channels corresponding to the context of the user-selected portion of the document; determine whether the set of collaboration channels corresponding to the context of the user-selected portion of the document is empty; create a new collaboration channel based on the context of the user-selected portion of the document in response to determining that the set of collaboration channels corresponding to the context of the user-selected portion of the document is empty; select one or more of the set of collaboration channels corresponding to the context of the user-selected portion of the document in response to determining that the set of collaboration channels corresponding to the context of the user-selected portion of the document is not empty; and establish a collaboration that communicates information about the user-selected portion of the document between the user and other users by utilizing the one or more of the set of collaboration channels corresponding to the context of the user-selected portion of the document.