Google is the most used search engine in the world (about 90% in Italy). Nowadays it is probably the most powerful, fast and rich of documents search engine (and it's free too), but Google is constantly argued because of its many unsolved problems (e.g. criteria of the algorithm PageRank, privacy, filter bubble).
Google is also a very big corporation that offers a lot of services like Google Maps, Gmail, Google+ (a social network), etc. Google Scholar and Google Books are two tools that can be very useful for an academic research.
