Which decade saw the introduction of bikinis in swimwear?

The 1940s is recognized as the decade when bikinis made their debut in swimwear, marking a significant shift in fashion and social norms. Specifically, the bikini was introduced in 1946 by French designer Louis Réard. This two-piece swimsuit was named after the Bikini Atoll, where atomic bomb tests were conducted, as it was believed to have a similarly explosive effect on fashion norms of the time.

The introduction of the bikini challenged conventional ideas of modesty and female body representation, reflecting the post-war era's changing attitudes towards women's roles and styles. This new swimwear became increasingly popular through the late 1940s and into the 1950s, eventually becoming a staple in beach fashion.

In contrast, the other decades did not see the bikini being formally introduced as a fashion item or widely accepted, as swimwear at the time consisted mostly of one-piece suits or more modest two-piece styles without the risqué cut associated with bikinis. Thus, the 1940s stands out as the pivotal decade for the bikini's arrival and subsequent acceptance in popular culture.