28. A volatile or non-volatile computer-readable storage medium storing one or more instructions which, when executed by one or more processors, cause the one or more processors to perform steps comprising: receiving one or more query terms of a query to a search engine that is capable of performing searches based on any one of a plurality of languages; selecting a particular language, from among the plurality of languages, based at least in part on both the one or more query terms of the query and at least one of: (a) whether the one or more query terms are encoded in ASCII, (b) a top-level domain of a particular URL, (c) a source IP address that is associated with a user entering the query, and (d) whether characters of the one or more query terms are in a specified subset of Unicode; based on having selected the particular language, performing a search for content items associated with the particular language based on the one or more query terms; and presenting, to the user, one or more content items that are associated with the particular language; wherein the content of the one or more query terms does not expressly state the particular language.
28. A volatile or non-volatile computer-readable storage medium storing one or more instructions which, when executed by one or more processors, cause the one or more processors to perform steps comprising: receiving one or more query terms of a query to a search engine that is capable of performing searches based on any one of a plurality of languages; selecting a particular language, from among the plurality of languages, based at least in part on both the one or more query terms of the query and at least one of: (a) whether the one or more query terms are encoded in ASCII, (b) a top-level domain of a particular URL, (c) a source IP address that is associated with a user entering the query, and (d) whether characters of the one or more query terms are in a specified subset of Unicode; based on having selected the particular language, performing a search for content items associated with the particular language based on the one or more query terms; and presenting, to the user, one or more content items that are associated with the particular language; wherein the content of the one or more query terms does not expressly state the particular language. 30. The computer-readable medium of claim 28 , wherein the particular language is determined based on a top-level domain of a particular URL.