Schools get the summer months off (usually July and August) as well as breaks for Easter and Christmas. These dates are generally followed even in countries with a large Muslim population, such as BiH and Albania.
Orthodox churches celebrate Easter between one and five weeks later than other churches.
Muslim regions celebrate two major festivals or bajrams: the end of Ramadan and the Feast of the Sacrifice. Muslim religious holidays follow the lunar calendar, which is 11 or 12 days shorter than the Gregorian calendar, so the dates of the bajrams fall 11 or 12 days earlier each (Gregorian) year. To make it even more interesting, the exact dates depend on the sighting of the new moon. In some cases, an imam from one town will spot a sliver of the moon a day earlier or later than his colleagues, so the local faithful will celebrate on a different day, which means that listed dates are often approximate.