A UNESCO World Heritage Site is a landmark or area recognized by the United Nations Educational, Scientific and Cultural Organization for its cultural, historical, scientific, or other forms of significance. These sites are deemed to have outstanding universal value and are protected under international treaties. The designation helps preserve these sites for future generations and promotes awareness of their importance. Examples include the Great Wall of China and the Pyramids of Egypt, which attract millions of visitors each year, highlighting the need for conservation and sustainable tourism practices.