From its website
Google Developer Groups (GDGs) are for developers who are interested in Google’s developer technology; everything from the Android, App Engine, and Google Chrome platforms, to product APIs like the Maps API, YouTube API and Google Calendar API.
A GDG can take many forms — from just a few people getting together to watch our latest video, to large gatherings with demos and tech talks, to events like code sprints and hackathons. However, at the core, GDGs are focused on developers and technical content, and the core audience should be developers.
The GDG has 355 (active and emerging) chapters in 99 countries for people interested in Google technology including Android, App Engine, Google Maps API, Google Apps API, and Google+
The Google Developers Group initiated the Women Techmakers in 2012 as a “five-episode series airing November 5th-9th daily at 2:30 PM PST (22:30 UTC), highlighting women in the technical space who are fearlessly innovating, honing technical expertise, and testing the boundaries of technology.” “These episodes are filmed and retained in Google Hangouts to attract girls and young women to enter the field of science and technology. ”