Short answers, pulled from the story.
IUPAP was founded in 1922, following a General Assembly of the International Research Council in Brussels where physicists declared that forming a physics union was imperative. The organization held its first General Assembly in Paris in 1923.
IUPAP's mission is to assist in the worldwide development of physics, to foster international cooperation in physics, and to help apply physics toward solving problems of concern to humanity. It pursues these goals by sponsoring international conferences, encouraging research and education, fostering the free circulation of scientists, and promoting international agreements on symbols, units, and standards.
IUPAP's 13 founding members were Belgium, Canada, Denmark, France, the Netherlands, the Empire of Japan, Norway, Poland, Spain, Switzerland, the United Kingdom, the United States, and the Union of South Africa.
IUPAP sponsors numerous prizes, including the Boltzmann Medal for statistical physics, the Fritz London Memorial Prize for low temperature physics, the Shakti Duggal Award for young cosmic ray physicists (established in 1983), and the Early Career Scientist Prize (formerly the Young Scientist Prize, renamed at the 2021 General Assembly). The Kennedy Reed Medal honors contributions to physics in developing countries, and the ICO Prize and ICO Galileo Galilei Award are given by the Affiliated Commission for Optics.
IUPAP issued a statement against the Russian military offensive in February 2022 while continuing to advocate for international scientific cooperation. The Union also extended an open offer for physicists from any country who feel excluded from academic exchange based on their affiliation or country of origin to apply to use IUPAP as their institutional affiliation.
IUPAP endorses approximately 30 international conferences each year across four categories: Type A general conferences drawing 750 to 1,000 attendees, Type B topical conferences drawing 300 to 600, Type C special conferences drawing 50 to 200, and Type D workshops in developing countries, with only one Type D event approved per year.