Urban infrastructure is an academic concept and research field investigating the essential physical systems and networks that enable the functioning, sustainability, and development of urban areas. This field examines the planning, design, construction, operation, maintenance, financing, governance, and interdependencies of diverse systems such as transportation, water supply, sanitation, energy, communication, and waste management. Key characteristics studied include their large-scale, capital-intensive nature, long lifespans, systemic interconnectedness, and critical role in supporting public health, economic activity, environmental management, and overall urban resilience and quality of life. Its significance lies in its fundamental contribution to urban form, economic competitiveness, social equity, and environmental quality, making it a critical area for policy, planning, and management research.