We hear the phrase every year, but what exactly is Earth Day? It's an annual event held on April 22nd to focus attention on the environment and how humans influence it. Now observed in nearly 200 countries, it began in 1970 as a day designed to teach American students about the importance of conservation. Over the next 20 years the event was almost forgotten, but it came back in a big way.

1990's "Earth Day 20" brought together over 200 million people in 141 countries. It made governments around the world realize the importance of recycling, and put the environment on the international stage. It also saw Earth Day become an annual event, rather than one held every ten years. Earth Day 2000 was even bigger, with over 5,000 groups in 183 countries taking part. The Internet was now the event's main organizing tool, and film star Leonardo DiCaprio was its host.

Some believe the choice of April 22nd as Earth Day shows Communist influence. April 22nd, 1970 was the 100th birthday of Soviet leader Vladimir Lenin. The event certainly goes beyond politics now, though, and is a rare example of international agreement.

我們每年都會聽到此名詞，但是到底何謂世界地球日？ 每逢4月22日，就是響應世界地球日的時刻，目的在於多加關懷環境議題，以及人類的行為對環境造成何種影響。現在將近200個國家落實此活動，其起源始於1970年，當時是為了教導美國學生瞭解環境保護的重要性。往後的20年左右，該活動幾乎遭人遺忘，卻以不同凡響的方式捲土重來。

1990年的「世界地球日20周年慶」，帶動141個國家超過2億人口留意此盛事。此現象讓全球各地的政府意識到資源回收的重要性，並使環保議題受到國際關注。世界地球日也因而成為一年一度的活動，而非每十年舉辦一次。2000年的世界地球日規模更加盛大，183個國家中，有超過5000個團體響應。網路世界是該次活動的主要統籌工具，而電影明星李奧納多• 狄卡皮歐更擔任活動主持人。

不過，有些人認為將4月22日選做世界地球日，足以顯見共產黨的影響力。因為1970年4月22日是蘇聯領導人列寧的100年誕辰紀念日。不過，世界地球日的意義現已超越政治，而且是國際間少數取得協議共識的活動。