1. A method performed by a computer system that comprises one or more processors and memory, comprising: detecting information specifying a domain name for one or more resources; searching a cache for cached content that is associated with the domain name for the one or more resources, with the cached content differing from the information specifying the domain name, and with the cache storing copies of content in the one or more resources obtained through periodic crawling of a network for the content in the one or more resources; retrieving, from the cache, the cached content associated with the domain name; determining a type of language used in the retrieved cached content that is associated with the domain name; and selecting, at least partly based on the determined type of language, an advertisement item for display in at least one of the one or more resources associated with the domain name.