FLUXNET started in 1997 and has grown from a handful of sites in North America and Europe to a current population exceeding 260 registered sites world-wide. Today, FLUXNET consists of regional networks in North America (AmeriFlux, Fluxnet-Canada, NEON), South America (LBA), Europe (CarboEuroFlux, ICOS), Australasia (OzFlux), Asia (China Flux, and Asia Flux) and Africa (AfriFlux). At each tower site, the eddy covariance flux measurements are made every 30 minutes and are integrated on daily, monthly and annual time scales. The spatial scale of the footprint at each tower site reaches between 200 m and a kilometer.