5月1日，国际劳动节，它是全世界工人阶级斗争的历史纪念，每个国家都很重视它，尤其是美国、加拿大、南非。1886年5月1日，以美国芝加哥为中心，美国大约有35万工人不顾反动军警的血腥镇压，实行了大规模的罢工和示威游行，要求改善劳动条件，实行八小时工作制。美国工人的英勇斗争得到了全世界各国工人阶级的支援，迫使资本家接受了工人提出的“每天工作八小时”的要求。为了纪念这次胜利，显示“全世界无产者，联合起来”的伟大力量，1889年7月，第二次国际代表大会决定把5月1日作为国际劳动节。1890年5月1日，欧美各国的工人阶级率先走向街头，举行盛大的示威游行与集会，争取合法权益从此，每逢这一天世界各国的劳动人民都要集会、游行，以示庆祝。

International Workers' Day（国际劳动节） is a celebration of the social and economic achievements of the international labor movement. International Workers' Day commonly sees organized street demonstrations by hundreds of thousands of working people and their labor unions throughout Europe and most of the rest of the world — though, as noted below, not in either the United States or Canada. More radical groups such as communists and anarchists are also given to widespread street protest on this day as well.

International Workers' Day was originally the commemoration of the Chicago riots（暴乱）of 1886: in 1889, the first congress of the Second International（第二国际）, meeting in Paris for the centenial of the French Revolution（法国大革命） and the Exposition Universelle (1889), following a proposal by Raymond Lavigne, called for international demonstrations on the 1890 anniversary of the Chicago riot. These were so successful that International Workers' Day was formally recognized as an annual event at the International's second congress in 1891. The May Day Riots of 1894 and May Day Riots of 1919 occurred subsequently.

In 1904, the International Socialist Conference meeting in Amsterdam（阿姆斯特丹） called on "all Social-Democratic Party organizations and trade unions of all countries to demonstrate energetically on May First for the legal establishment of the 8-hour day, for the class demands of the proletariat, and for universal peace." As the most effective way of demonstrating was by striking, the congress made it "mandatory upon the proletarian organizations of all countries to stop work on May 1, wherever it is possible without injury to the workers."

International Workers' Day has long been a focal point for demonstrations by various socialist, communist, and anarchist groups. In some circles, bonfires are lit in commemoration of the Haymarket Riot, usually right as the first day of May begins.

Due to its status as a celebration of the efforts of workers and the socialist movement, International Workers' Day is an important official holiday in Communist countries such as the People's Republic of China, Cuba, and the former Soviet Union(前苏联) . International Workers' Day celebrations typically feature elaborate popular and military parades in these countries.

In countries other than the United States and Canada, resident working classes fought hard to make International Workers' Day an official holiday[citation needed], efforts which largely succeeded. For this reason, in most of the world today, International Workers' Day is marked by massive street rallies led by workers, their trade unions, anarchists and various socialist and communist parties.

The First and Second Red Scare periods ended International Workers' Day as a mass holiday in the United States, which now celebrates its Labor Day on the first Monday of September, due to its importance in Communist countries.