The Treaty of Nice was signed in 2001 and aimed to reform the structure of the European Union (EU) to prepare for the enlargement that would include several new member states. It made changes to the voting system in the Council of the European Union, allowing for a more balanced representation of both large and small countries. Additionally, the treaty enhanced the powers of the European Parliament and established new procedures for decision-making. It also introduced measures to improve cooperation in areas like justice and home affairs, helping the EU to function more effectively as it expanded.