The Treaty of Lisbon is an international agreement that was signed on December 13, 2007, and came into effect on December 1, 2009. It aimed to enhance the efficiency and democratic legitimacy of the European Union (EU) and to improve its decision-making processes. The treaty introduced changes to the structure and functioning of the EU, including the establishment of a permanent president of the European Council and the creation of the position of the High Representative for Foreign Affairs. Additionally, the Treaty of Lisbon expanded the powers of the European Parliament and introduced the principle of "double majority" voting in the Council of the European Union. It also included provisions for greater citizen participation and the protection of fundamental rights. Overall, the treaty sought to streamline EU governance and make it more responsive to the needs of its member states and citizens.