IESO meaning in International ?

The International Earth Science Olympiad (IESO), one of the thirteen International Science Olympiads, is an annual competition for secondary school students that tests their abilities in disciplines such as geology, meteorology, environmental science, and terrestrial astronomy. Students who are winners of the respective national competitions are invited to participate in the IESO, and all interested countries are encouraged to contribute to the IESO. The IESO is one of the only three International Science Olympiads (along with the International Linguistics Olympiad and International Olympiad on Astronomy and Astrophysics) to include an International Team Competition.

It is one of the major activities of the International Geoscience Education Organization – IGEO that aims at raising student interest in and public awareness of Earth sciences, as well as to enhance Earth science learning of students.