Google is a web-search engine that provides many different options for customized searching.
Google Books is a service that searches the full text of books and magazines that Google has scanned and stored in its digital database. The project began in 2004 as the Google Print Library Project through a partnership with several high-profile university and public libraries. Books are made available in the database in two ways. They are either submitted by publishers and authors, through the Google Books Partner Program or through Google's library partners as part of the Library Project. As of 2013, over 30 million books have been scanned.
Google Scholar is a search engine that indexes the full text of scholarly literature. This includes most peer-reviewed online journals of scholarly publishers, plus scholarly books and other non-peer reviewed journals. Google Scholar allows users to search for digital or physical copies of articles, whether online or in libraries.
Google Play is a digital distribution platform for applications operated by Google. The service allows users to browse and download applications as well as music, magazines, books, movies, and television programs.
HathiTrust is a large-scale collaborative repository of digital content from research libraries. It includes over 60 research libraries across the United States, Canada, and Europe including the University of Pittsburgh. As of January 2012, HathiTrust comprised over 10 million volumes, over 2.7 million of which are public domain.
The Internet Archive is a non-profit digital library that provides permanent storage of and free public access to collections of digitized materials, including websites, music, moving images, and nearly 3 million public-domain books. It allows the public to upload and download digital material to its data cluster, but the bulk of its data is collected automatically by its web crawlers.
Historic Pittsburgh is a comprehensive collection of local resources that supports personal and scholarly research of the Western Pennsylvania area.
The University Library System has created a guide specifically covering all ebook sources and ebook-related questions with helpful links and tips.