Earth Day describes is an annual event, celebrated on the 22nd April, when "over a billion people in 190 countries take action for Earth Day. From San Francisco to San Juan, Beijing to Brussels, Moscow to Marrakesh, people plant trees, clean up their communities, contact their elected officials, and more—all on behalf of the environment".
It was initiated by social movement activists and encourages people to participate through an online platform, organising & campaigning, and special events. Earth Day is global in orientation and concerned with environment & sustainability.
It was launched in 1970 and is ongoing.