This lecture provides a comprehensive overview of trade union organization, covering its structural foundations, centers of responsibility, and core union principles such as social justice, collective leadership, and democratic centralism. It explores both national and international legal frameworks that safeguard union rights and freedoms. The lecture also details the conditions and steps for establishing unions, the types of membership, democratic practices in meetings and elections, and the financial management system within unions. Additionally, it emphasizes gender equality in union structures and highlights the importance of autonomy and democracy as key pillars in ensuring effective representation and advocacy for workers' rights.