Dadaism was a movement in art and writing in Europe in the early 20th century, starting during the First World War, around 1916 in Zurich. The artists had watched a war kill millions of people, and they decided that the polite, serious culture that produced such a war had lost the right to be taken seriously. So they made art that refused to make sense: nonsense poems built from random words, a picture cut up and glued back together, and most famously an ordinary factory-made object simply put in a gallery and called art. The aim was to shock people and to break the accepted rules about what art is and who decides. Dadaism did not last long as an organised movement, but it changed everything after it — surrealism grew directly out of it in the 1920s, and modern conceptual art and performance art still live on ideas Dada started. Today people also use 'Dadaism' loosely for anything deliberately absurd or anti-rules, and the adjective 'Dadaist' can just mean 'wildly nonsensical'. You will see the name written with or without a capital D.

達達主義（二十世紀初的前衛藝術運動）