What is digital library? There is no unique definition for it. If we go to Wikipedia, I snipped the important definition as follows; “a library in which collections are stored in electronic media formats and accessible via computers. The electronic content may be stored locally, or accessed remotely via computer networks”. From the scope of Digital Library from Stanford University would say; "at Stanford University, some discussion was held as to what did we mean by the term "digital library". It would be valuable to document a common understanding of the term, but agreed that we could not and would not aim for a general consensus. The term "Digital Library" has a variety of potential meanings, ranging from a digitized collection of material that one might find in a traditional library through to the collection of all digital information along with the services that make an information useful to all possible users. The following definition was proposed; The Digital Library is the collection of services and the collection of information objects that support users in dealing with information objects and the organization and presentation of those objects accessible directly or indirectly via electronic or digital means.
There are many more definition from other sources as well such as from eEurope Action Plan, Digital Strategy Programmes which more simpler meaning of Digital Library which is "Digital libraries are organized collections of digital content made available to the public”.
Digital libraries are large, organized collections of information objects. Well-designed digital library software and services has the potential to enable non- specialist people to conceive, assemble, build, and disseminate new information collections. This has great social import because, by democratizing information dissemination, it provides a counterbalance to disturbing commercialization initiatives in the information and entertainment industries. This essay
References: Digital library - Wikipedia, the free encyclopedia. (n.d.). Retrieved June 3, 2014, from http://en.wikipedia.org/wiki/Digital_library