An initiative of the League of Conservation Voters (LCV) and other environmental groups to support political candidates committed to environmental policies. This platform is centered
around a website where (qualifying?) politicians can manage a profile page and solicit donations. Fundraising, as hinted in the 'Give Green' name, is the primary aim of the site, but its implied endorsement of the candidates listed therein and various links and elements of the site provide opportunities for engaging voters and 'ambassadors' in other ways.
[as they'd say on Wikipedia, "This page needs work"... authoritative sources and corrections are welcome]
Give Green started circa 2011, initially at the URL givegreen.zissousecure.com, and as a project of the LCV Action Fund alone. Around 2014, the URL changed to givegreen.com and the NRDC Action Fund, later (2017 ?) joined by NextGen Climate / NextGen America. Also the site which originally supported both local and national candidates was split, where State-level candidates were now listed on givegreenstates.org.