VIRTUAL LIBRARY

A virtual Library also known as a Digital Library or an Electronic Library may be defined as the online facility provided by a conventional library to read books and access other facilities or it may mean a website which offers links to various sites with a large store of information in a catalogued or archived form. The term is more often used to refer in a collective manner to the entire number of online books and other literary material related to any subject available on the Internet.

A virtual library generally is part of a network with linkages to other libraries providing universal access to information though virtual libraries which are off-shoots of conventional ones require you to be a member first. Universities that offer a distance education facility more often than not have a virtual library for their students.
An organization, which might be virtual, that comprehensively collects, manages and preserves for the long term rich digital content, and offers to its user communities specialized functionality on that content, of measurable quality and according to codified policies.

Example :-

The WWW Virtual Library: Science Fairs
Some virtual libraries concentrate on only one subject. This virtual library, devoted to science fairs, is an example of a specialized virtual library.  The virtual library is a collection of Web links, and specializes in just-for-me learning for people with an interest in this topic.

Library in the Sky
This is a database of interesting and useful educational Web sites for those involved in the field of education. The main benefit of this type of virtual library for the learner is the organization and the management of the resources and the just-for-me learning that it enables.

Halifax Library E-Branch
The Halifax public library maintains an e-branch, a virtual library where people can search the library catalog, ask reference questions, or search for articles from the electronic databases for which the library has purchased licences. There are different levels of services for people with library cards and people without. 

NovaNet
Novanet is a consortium of academic libraries in Nova Scotia who cooperate to provide access to information and knowledge for the benefit of their user communities.