OAuth is just an API that Google gives out to developers to let them authenticate Google accounts in other manners other than just going on google.com - for example through a programmatic way. Authentication is the basis of it, but through OAuth you're able to retrieve lots of information from a specific Google account (calendar info, contacts etc.). Google maps supports OAuth 2.0 as the recommended authentication mechanism for all of its APIs. By focuses on client developer simplicity while providing specific authorization flows for web applications, desktop applications, mobile phones, and living room devices.