Sunlight is a multi-dimensional occurrence that has the potential to improve the well-being, health, and interaction of occupants with the external surroundings due to its dynamic qualities in terms of both illumination and temperature. It is gift to human from Mother Nature, it have wide range of spectrum which cannot be replaced by artificial light. Daylight exhibits dynamism, with its intensity, colour, and temperature undergoing continuous fluctuations over time. To measure daylight various metrics are being used. The concept of daylight metrics has emerged as a pivotal aspect in architectural and interior design, offering a systematic approach to quantifying and optimizing the utilization of natural light within built environments. Daylight metrics encompass a range of measurements and calculations that evaluate the quality, quantity, distribution, and performance of natural light in indoor spaces. This comprehensive review paper focuses on the metrics related to daylight quantity, light uniformity, and direct sunlight, elucidating their advantages and constraints through their mathematical formulations. It provides guidance on their application, along with identifying areas that require enhancement to facilitate their utilization within optimization processes for building design.