Environment Online (shortly ENO ) is a global school network and web community for sustainable development established in year 2000 in Finland. Environmental themes are studied throughout the school year and campaigns arranged simultaneously around the world. Over 10 000 schools from 150 countries have taken part since the beginning. In addition to schools, cities and municipalities who want to support ENO schools have joined ENO Green Cities Network.
The ENO programme is coordinated and maintained by ENO Programme Association based in the city of Joensuu, Finland. Schools have made concrete deeds for the environment such as having planted 30 million trees so far. ENO has many national and international recognitions.