Google I/O is an annual developer-focused conference held by Google in San Francisco, California. Google I/O features highly technical, in-depth sessions focused on building web, mobile, and enterprise applications with Google and open web technologies such as Android, Chrome, Chrome OS, Google APIs, Google Web Toolkit, App Engine, and more.
Google I/O was started in 2008. The "I" and "O" stand for input/output, and "Innovation in the Open". The format of the event is similar to that of the Google Developer Day.
Read more about Google I/O: 2008 (May 28–29, 2008), 2009 (May 27–28, 2009), 2010 (May 19–20, 2010), 2011 (May 10–11, 2011), 2012 (June 27–29, 2012), 2013 (May 15–17, 2013)