Before defining the essence and features of the electronic library collection, it is necessary to remove the issues related to the concept of an electronic document and a document as a more general concept and collection-building element. The regulatory documents – the Law on Information, Informatization and Information Protection, the Law on Librarianship, the Law on mandatory copies of documents, as well as state standards for information, library, bibliographic activities – make the significant foundation for the theory and practice. Based on their analysis, the author suggests to consider information or an object that corresponds to the profile of a library to be a potential document of this library collection. The document that belongs to the library collection is a real document. Within this definition, the focus is transferred to the specific nature of individual library, correspondingly, each library would give its own definition of the document. Thus, the concept of “electronic document of the library collection” has to be built on the basis of the document concept. The former defines the wider concept of “electronic library collection” interpreted as “the ordered collection of electronic documents”. This concept series is sufficient for the electronic library collection science, therefore all other innovations – “information object”, “information unit”, “electronic library object”, “information resource” are to be questioned or rejected. Information as a reality is disembodied, it cannot be detected in its pure form, hence many terms formed from it (information retrieval system, information transmission, information processing, storage of information, etc.) are inappropriate and should be replaced by that based on the root of the word “document”.