The author examines the development of the basic concepts of indexing information resources using classifications and dictionaries of information retrieval languages. The impact of digital communications and the Internet on the indexing methods in the information environment, including the libraries, is emphasized. The modern library collections comprise various types of resources, both traditional paper publications and digital resources of various types, widely available on the Internet. In these conditions, harmonization of indexing methods with the principles of Internet information retrieval grows in importance. The author discusses the regulatory framework for indexing in the library sector and its relationship with Internet standards within the concept of Semantic Web. The author reviews the main stages of the development of the regulatory framework both on the international level and in this country. The author emphasizes the need to study the experience of other organizations in the field of standardization for further development of indexing technology.