UNESCO (United Nations Educational Scientific and Cultural Organization) is a specialized organization in the United Nations system whose main role is to contribute to peace and security in the world. Great attention is given to the preservation of natural heritage, and programs and strategies are continuously developed to preserve nature and its original state. There are six natural areas in Croatia under UNESCO protection, and there will certainly be more in the future. In order for a monument or area to be inscribed on the World Heritage List, certain conditions or criteria must be met. The basic criterion, i.e. the first step in registering a locality on the World Heritage List, is that it is on the Tentative List in order for its nomination to be taken into account at all. The tentative list is a temporary list of sites that member states consider worthy of nomination for the World Heritage List, and sites on it can always be added or removed. It is also very important that the site has exceptional value and that it meets at least one of the ten criteria of the World Heritage Committee, which are divided into natural and cultural. The process of registering a site on the World Heritage List is very complex and takes at least eighteen months. It is important that the localities that are under the protection of UNESCO are constantly taken care of, because the competent authorities always monitor the conditions of these localities and take care of whether they are still in the condition they were in and whether they are endangered. If it happens that the site is endangered or that it is not properly cared for, it can be removed from the World Heritage List. UNESCO stamps are awarded to world heritage sites in order to somehow mark their importance and universal value. They can be of different shapes and usually have the UNESCO logo or the inscription UNESCO WORLD HERITAGE on them.