1. A computer-implemented method comprising: determining a particular language based at least in part on both content of text submitted by a user and at least one of: (a) whether the text is encoded in ASCII, (b) a top-level domain of a particular URL, (c) a source IP address that is associated with the user, and (d) whether characters of the text are in a specified subset of Unicode; and presenting, to the user, one or more content items that are associated with the particular language. wherein the content of the text does not expressly state the particular language.