Laser speckle contrast imaging (LSCI) is a powerful tool for full-field imaging of blood flow, first introduced in the 1980s. It has gained increased attention due to its rapid adoption for blood flow studies in the brain. This review discusses the underlying physics of speckle contrast imaging, recent developments to improve the quantitative accuracy of blood flow measures, and applications in neuroscience, dermatology, and ophthalmology. LSCI works by analyzing the temporal and spatial fluctuations of speckle patterns produced by coherent light scattering from moving particles. The speckle contrast, defined as the ratio of the standard deviation to the mean intensity, is used to quantify blood flow. The theoretical basis of LSCI is rooted in dynamic light scattering and the analysis of temporal and spatial statistics of speckle patterns. Recent advancements include improved algorithms for calculating speckle contrast to enable real-time visualization and the use of LSCI in multimodal imaging schemes to obtain additional information about tissue. Applications of LSCI include imaging blood flow in the retina, skin, and brain. In the brain, LSCI has been used to study functional activation, cortical spreading depression, and stroke. It provides high spatial and temporal resolution, allowing for the visualization of blood flow changes in response to stimuli and the assessment of hemodynamic responses. LSCI is also used to monitor skin perfusion and retinal blood flow, offering insights into various medical conditions. LSCI has been combined with other optical techniques such as multispectral reflectance imaging (MSRI) and phosphorescence quenching measurements to simultaneously measure multiple hemodynamic and metabolic parameters. This combination enhances the ability to study neurovascular coupling and the effects of various pathologies on blood flow. Despite its advantages, LSCI faces challenges such as static scattering and the need for proper calibration to ensure accurate measurements. Overall, LSCI is a valuable tool in biomedical imaging for studying blood flow dynamics in various tissues and applications.Laser speckle contrast imaging (LSCI) is a powerful tool for full-field imaging of blood flow, first introduced in the 1980s. It has gained increased attention due to its rapid adoption for blood flow studies in the brain. This review discusses the underlying physics of speckle contrast imaging, recent developments to improve the quantitative accuracy of blood flow measures, and applications in neuroscience, dermatology, and ophthalmology. LSCI works by analyzing the temporal and spatial fluctuations of speckle patterns produced by coherent light scattering from moving particles. The speckle contrast, defined as the ratio of the standard deviation to the mean intensity, is used to quantify blood flow. The theoretical basis of LSCI is rooted in dynamic light scattering and the analysis of temporal and spatial statistics of speckle patterns. Recent advancements include improved algorithms for calculating speckle contrast to enable real-time visualization and the use of LSCI in multimodal imaging schemes to obtain additional information about tissue. Applications of LSCI include imaging blood flow in the retina, skin, and brain. In the brain, LSCI has been used to study functional activation, cortical spreading depression, and stroke. It provides high spatial and temporal resolution, allowing for the visualization of blood flow changes in response to stimuli and the assessment of hemodynamic responses. LSCI is also used to monitor skin perfusion and retinal blood flow, offering insights into various medical conditions. LSCI has been combined with other optical techniques such as multispectral reflectance imaging (MSRI) and phosphorescence quenching measurements to simultaneously measure multiple hemodynamic and metabolic parameters. This combination enhances the ability to study neurovascular coupling and the effects of various pathologies on blood flow. Despite its advantages, LSCI faces challenges such as static scattering and the need for proper calibration to ensure accurate measurements. Overall, LSCI is a valuable tool in biomedical imaging for studying blood flow dynamics in various tissues and applications.