In wars, many people have to fear for their lives. They are forced to leave their native country temporarily or forever. They become refugees. In the past, there have often been large waves of thousands or millions of refugees looking for a safe place to live. There are people who flee from persecution by government troops, or who have to leave their homes and villages because of power struggles between warring groups. Refugees who are made homeless within their own countries are often called "internally displaced persons (IDPs)”. The many people who come to Europe and Germany from other countries looking for asylum are refugees as well. There are many different reasons why people have to leave their homelands. Many are persecuted because of their nationality, their religion or their political views. Others feel forced to flee because of bad economic conditions in their countries or because of a civil war. And still others have to leave their countries because natural disasters such as earthquakes or floods have made it impossible to live there. The UN has a High Commissioner for Refugees (UNHCR) to deal specifically with the problem of refugees and has set up various aid organisations. According to UNHCR estimates, around 45.2 million people worldwide, including IDPs, can be considered as refugees.