IIO meaning in International ?

The International Olympiad in Informatics (IOI) is an annual competitive programming and one of the International Science Olympiads for secondary school students. It is the second largest science olympiad, after International Mathematical Olympiad, in terms of number of participating countries (83 at IOI 2017). The first IOI was held in 1989 in Pravetz, Bulgaria.

The contest consists of two days of computer programming/coding and problem-solving of algorithmic nature. To deal with problems involving very large amounts of data, it is necessary to have not only programmers, "but also creative coders, who can dream up what it is that the programmers need to tell the computer to do. The hard part isn't the programming, but the mathematics underneath it." Students at the IOI compete on an individual basis, with up to four students competing from each participating country (with 81 countries in 2012). Students in the national teams are selected through national computing contests, such as the Australian Informatics Olympiad, British Informatics Olympiad, Indian Computing Olympiad or Bundeswettbewerb Informatik (Germany).

The International Olympiad in Informatics is one of the most prestigious computer science competitions in the world. UNESCO and IFIP are patrons.