A platinum jubilee is a celebration held to mark an anniversary. Among monarchies, it usually refers to a 70th anniversary.
The next currently reigning monarch who would celebrate a platinum jubilee is Queen Elizabeth II, should she still be reigning on 6 February 2022. Furthermore, Queen Elizabeth II and Prince Philip, Duke of Edinburgh will, should they both still be alive and married to each other on 20 November 2017, celebrate a platinum wedding anniversary.
In South Asian usage, a "platinum jubilee" refers not to an anniversary, but the celebration of 75 weeks. For instance, in Pakistan and India, a platinum jubilee film is one shown in cinemas for 75 weeks or more. The success measure for a 'super hit film' is minimum six months release on its main cinema.
The term is uncommon in the United States, where a 75th anniversary is termed a "diamond jubilee" (in reference to an event only).
The next level of celebration, an anniversary of 100 years, is simply called a centenary.