A non-invasive optical method called diffuse correlation spectroscopy (DCS) analyses scattered light to determine the perfusion of tissue. Traditional DCS measures, restricts their application in clinical trials or tiny animal models and to get over these drawbacks the study focused on increasing its adaptability for different applications with different potential methods. Time-domain difuse correlation spectroscopy (TD-DCS), a cutting-edge technique, can improve the accuracy of BF measurements. Blood Flow Index (BFI) can be investigated using diffuse correlation spectroscopy (DCS), but its limited sensitivity and susceptibility to changes in tissue characteristics make it difficult to obtain accurate results. Non-invasive insights into dynamic biological processes in deep tissues are discussed by different researchers through optical technology. The goal of methods like diffuse correlation spectroscopy (DCS) is to quantify variations in blood flow. In order to provide massively parallel single-photon detection, it is advisable to use of integrated Single-Photon Avalanche Diode (SPAD) arrays to detect deep tissue events accurately. DCS analyses with coherent near-infrared light to track microvascular blood flow deep within tissues. Microvascular blood flow is essential for supplying tissues with nutrition, oxygen and eliminating metabolic waste products, maintaining the organs’ healthy operation. The proposed review article has focused on the importance of a non-invasive, risk-free, and affordable substitute for continuous blood flow monitoring of the patient to assess the brain activity, detection of cancer and the investigation of muscle function.