Functional MRI (fMRI) is a neuroimaging technique that allows researchers to non-invasively measure and map brain activity by detecting changes in blood flow. It is commonly used in cognitive neuroscience and psychology to study which areas of the brain are active during specific tasks or mental processes. By measuring the changes in blood flow that occur when a particular brain region is active, fMRI provides valuable insights into how different brain regions function and interact with each other. This technique has been instrumental in advancing our understanding of brain function, cognition, and behavior.