Kostadin Vodenicharov writes: The International Olympiad in Informatics (IOI) is considered one of the most prestigious programming contests in the world. Currently the 21st IOI is being held in Plovdiv, Bulgaria (which was the country that also hosted the 1st IOI) from 8th to 15th August. High school students from all over the world have gathered to put their programming skills to the test. Everyone else who wishes to participate can do it in the online contest which will run in parallel with the real one and will present the same tasks to be solved. The competition itself is going to take place on Monday 10th August and Wednesday 12th August from 9:00 to 14:00 EEST (UTC+3). For more information visit the IOI 2009 website.