This chapter introduces the foundational concepts of Zero Energy Buildings (ZEBs), focusing on their definition, energy balance principles, and various international standards and certifications. It highlights the limits of energy use in ZEBs and the importance of ZEBs in mitigating urban energy consumption and greenhouse gas emissions, with an emphasis on energy-efficient technologies and renewable energy integration. The discussion covers regulatory frameworks and some trends and challenges associated with achieving net zero energy status in buildings worldwide. To drive the adoption of ZEBs, global cooperation is essential to implement effective policies, harmonize standards, provide education, and foster innovation.