Deferent between Electronic library, Digital library & Virtual library

Library:-

A library is an organized collection of items of various formats (books, journals, videos, CD-ROMs, etc.) along with the services required to make them available to a given user group or groups. It is not a collection of programming routines, at least in this context.

Electronic library:

An electronic library is a library consisting of electronic materials and services. Electronic materials can include all digital materials, as well as a variety of analog formats that require electricity to use. For example, video tapes are an analog format that requires electronic equipment to view. Thus the term "electronic library" encompasses all the material that can be held by a "digital library", and is therefore more inclusive. It is, however, out

Digital library:-

A digital library is a library consisting of digital materials and services. Digital materials are items that are stored, processed and transferred via digital (binary) devices and networks. Digital services are services (such as reference assistance) that are delivered digitally over computer networks. One of the best examples of a digital library is the U.S. Library of Congress American Memory collection.

Virtual library:-

Both digital and electronic libraries can be virtual libraries if they exist only virtually -- that is, the library does not exist "in real life." For example, a virtual library can consist of material from a variety of separate libraries that are organized in a virtual space using computers and computer networks. One of the best examples of a virtual library is the Networked Computer Science Technical Reports Library (NCSTRL).