The concept of a Sharia compliant financial system has been a frequently discussed topic among scholars, bankers and media since the 1960th. It origins from the prohibition of interest, riba, which is stated in the Quran. Islamic banking is spread across the Muslim world and also exists in some western countries. This paper will try to create an image of what Islamic banking is in theory and in practice. This will be done by looking into the different methods of interest free banking, the Quran and the annual reports of four Islamic banks in different countries.