Today, the financial sector may be considered as the most mature sector compared to other economic sectors in the Arab economy. It uses local as well as foreign currencies in matter of exchanges and in measuring value of investment. The financial sector offers services through the process of buying money, financial instruments and securities or financial services in certain situation, and then reselling these money or financial instruments or services in another situation. The institutions that provide such services are called intermediary financial institutions, while the places of selling and buying money and financial instruments are known as financial markets. Accordingly, the financial sector includes besides the national currency, two major parts, financial markets and financial institutions, which have different merits, functions and mechanisms. Thus, this book is devoted to the financial institutions besides the issue of national currency in the Arab economy.