The world is full of authorities who promise to behave randomly: commercial lotteries worth millions of euros, randomized audits, school assignments, draws for international sports tournaments, or choosing travelers for secondary security screening.
More technically speaking, randomness is a requirement in many algorithms and hence verifiable randomness is a prerequisite for algorithmic transparency. Yet today authorities typically provide no evidence that they are behaving randomly. If any evidence is provided, it is typically in the form of a physical randomness process such as rolling dice.
Joseph describes the cryptographic foundations by which we can provide stronger evidence to verify that authorities are generating randomness fairly.