In trying to think the best way to explain it I thought it best to just let them do it from their about page: Link to it directly here:
About the Internet Archive
The Internet Archive is a 501(c)(3) non-profit that was founded to build an Internet library. Its purposes include offering permanent access for researchers, historians, scholars, people with disabilities, and the general public to historical collections that exist in digital format. Founded in 1996 and located in San Francisco, the Archive has been receiving data donations from Alexa Internet and others. In late 1999, the organization started to grow to include more well-rounded collections. Now the Internet Archive includes texts, audio, moving images, and software as well as archived web pages in our collections, and provides specialized services for adaptive reading and information access for the blind and other persons with disabilities. Why the Archive is Building an 'Internet Library'
Libraries exist to preserve society's cultural artifacts and to provide access to them. If libraries are to continue to foster education and scholarship in this era of digital technology, it's essential for them to extend those functions into the digital world.
Many early movies were recycled to recover the silver in the film. The Library of Alexandria - an ancient center of learning containing a copy of every book in the world - was eventually burned to the ground. Even now, at the turn of the 21st century, no comprehensive archives of television or radio programs exist.
But without cultural artifacts, civilization has no memory and no mechanism to learn from its successes and failures. And paradoxically, with the explosion of the Internet, we live in what Danny Hillis has referred to as our "digital dark age."
The Internet Archive is working to prevent the Internet - a new medium with major historical significance - and other "born-digital" materials from disappearing into the past. Collaborating with institutions including the Library of Congress and the Smithsonian, we are working to preserve a record for generations to come.
Open and free access to literature and other writings has long been considered essential to education and to the maintenance of an open society. Public and philanthropic enterprises have supported it through the ages.
The Internet Archive is opening its collections to researchers, historians, and scholars. The Archive has no vested interest in the discoveries of the users of its collections, nor is it a grant-making organization.
At present, the size of our Web collection is such that using it requires programming skills. However, we are hopeful about the development of tools and methods that will give the general public easy and meaningful access to our collective history. In addition to developing our own collections, we are working to promote the formation of other Internet libraries in the United States and elsewhere.
Find out
as well as our user forums
This books set in Paris during the 1930's is one of the neatest works of art, history and fiction! 
