Google Books is an extensive books and magazines search engine that is maintained by Google. Users can search for books online, browse them on the website if the publishers or authors have given permission, look at references or buy or borrow it. The service became more interesting to a lot of readers thanks to the recent announcement that more than 1 million public domain books have been added to the library of available books.
The biggest benefit for searchers is that the full text is available at the website. The text can either be viewed online or downloaded in pdf format to a local computer system instead.
Books that are available completely for online viewing and downloading are marked with a green full view text. A search for classics like Romeo and Juliet, Hamlet or Faust will reveal search results that include full versions but also books with limited or no preview. It is however safe to say that most classic books are provided in at least one full view edition.
The advanced search parameters can be used to search only for books or magazines that are available completely on the website. A few thousand books are usually available in full view if the name of a mastermind like Goethe, Schiller or Shakespeare is entered. Modern books on the other hand are usually not available as full versions.
You can also just browse the selection on Google Books which may be useful if you do not have a particular book or topic that you are interested in. Google displays magazines, classics and topic related books on the browse page that you can go through to get inspired.