International double taxation occurs when the same person or company is taxed in more than one country. Double Taxation Agreements (DTAs) are crucial in reducing this issue, with over 3000 in place worldwide. If no DTA exists, countries have methods to prevent double taxation, like total exemption or tax credits. The most common method used is exemption with progressivity for some public functions, while the fourth method (partial tax credit) is often used for income earned abroad.