For more than a century, the World Glacier Monitoring Service (WGMS) and its predecessor organizations have been compiling and disseminating standardized data on glacier fluctuations. Thereto, the WGMS annually collects glacier data through its scientific collaboration network that is active in more than 30 countries. This international effort has resulted in unprecedented datasets of glacier distribution and changes - freely available for scientific and educational purposes: www.gtn-g.org