1. A computer-implemented method of recognizing a first language used in information content, comprising: at a computer having one or more processors and memory for storing programs to be executed by the one or more processors: integrating a first vocabulary list and a second vocabulary list that are built based on a first language and a second language, respectively, into a comprehensive vocabulary list, wherein the integrating includes analyzing the first vocabulary list in view of the second vocabulary list to at least identify a first vocabulary sub-list, in the comprehensive vocabulary list, that is used in the first language, but not in the second language; identifying, within the information content, a plurality of expressions that are included in the comprehensive vocabulary list; identifying, within the plurality of expressions, a subset of expressions that are included in the first vocabulary sub-list; determining that a total frequency of occurrence of the subset of expressions within the information content meets predetermined occurrence criteria; and in accordance with the determination, determining that the information content is composed in the first language.