Google has launched a service that lets people download and print copies of classic books free of charge.

Google Book Search includes many of the world's most well-known books that are out of copyright, thanks to the company's ongoing collaboration with many University libraries such as Harvard and Oxford.

The aim of this Partner Program is to digitise major classics, as well as many popular books, and make them accessible to anyone.

"Public domain books include both well-known classics and less well-known books on every conceivable subject," said Sid Verba, Director of the Harvard University Library which is a partner in the Google Books Library Project.

"Since people can search the full text of these books, they can find previously buried information about historical events or people, places of interest and matters cultural or scientific.

"What has been tucked away in large research library collections and available only to a few, can now be discovered and read by people everywhere."

However, Google Book Search does not enable people to download any books under copyright. If the publisher or author has given Google Book Search permission through its Partner Program, people will only be able to view snippets or a few full pages from the book.

If this is not the case, the service will still display basic bibliographic information. In all cases, if people want to buy a book in or out of copyright that is still in print, the search provides links that lead directly to online bookstores that sell the titles or libraries that hold copies.

If the book is out of copyright, such as The Complete Works of William Shakespeare, the Download button is shown. Clicking on this will download a PDF file to the user's computer, where the book can be read offline, saved for later or a paper version printed.

A point to remember is many of the books shown on Google Book Search will be academic treatises or commentaries of the original work by current authors and still under copyright.