The author examines e-libraries as a subdivision of the new discipline of e-librarianship. The e-libraries as a particular subject of the library information environment emerged in 1990s, and in the mid-decade, the Russian National Public Library for Science and Technology (RNPLS&T) introduced its first e-collections. In 2020–2022, within the framework of the new research theme “Electronic Librarianship”, the RNPLS&T was developing the subjects of e-librarianship entity and definition, as well as of the terminological system. Today, the RNPLS&T’s research team has been preparing the multi-authored monograph “Electronic Librarianship”. The author discusses definitions for e-libraries offered by several scientists, with the preference given to that introduced in the textbook “Electronic libraries. Information and communication environment” [in Russian]. The author characterizes the major e-libraries, both national and global. Further intensive development and improvement of e-libraries is beyond doubt. The author suggests that the National Electronic Library (NEL) and Open Information Archives are to play the leading role in this process. The e-library is one of the subjects of studies in the area of e-librarianship. The generic affinity of the concepts of “library” and “e-library” is emphasized, which makes the e-librarianship the subdiscipline of general librarianship. Meanwhile, the e-librarianship covers a particular wide substantive area. The e-librarianship structure has to become the focus of further studies. The terms “e-library” and “digital library” are specified. The key trends of developing e-libraries as a component of library systems and libraries in the digital environment are defined, e. g. consolidation of providers of e-resource management systems, introduction of open source projects and information systems to support science, etc. Today, almost every university (high school), research institute, large or even medium-size library get their e-libraries, which stipulates and actualizes the development of new discipline of e-librarianship by RNPLS&T’s team. The modern libraries’ integration into the general information space is the key to further success. The article is prepared under the Government Order No. 075-01235-23-01 of August 9, 2023, theme No. 1021062311368-2-5.8.3 “Development pf electronic librarianship as a scientific and academic discipline in the circumstances of transforming library collections, reference, bibliographic and document services in the digital environment (FNEG-2022-0004)”