The origins of the rainbow peace flag are ambiguous. Some say that the use of the rainbow originates from the bible, when God created a rainbow for Noah to show that there would never again be another flood like the one that had happened. Others argue that it represents the different aspects of humanity (age, race, religion) all coming together. The International Co-operative movement flew a rainbow flag during their first ‘Co-operators’ day in July 1923 to symbolise the movement's ideas of international solidarity, economic efficiency, equality, and world peace.
However, the first use of the flag during a peace rally was in Italy in 1961, inspired by similar multi-coloured flags used in demonstrations against nuclear weapons. It became popular with the Pace da tutti i balconi ("peace from every balcony") campaign in 2002, started as a protest against the impending war in Iraq.
This flag has been adopted internationally as a symbol of the peace movement.