Functional imaging is a medical imaging technique that allows researchers and doctors to observe and measure brain activity. It provides insights into how different areas of the brain work during various tasks or in response to stimuli. Common methods include fMRI (functional Magnetic Resonance Imaging) and PET (Positron Emission Tomography), which visualize changes in blood flow or metabolic activity. These techniques are crucial for understanding brain functions, diagnosing neurological disorders, and guiding treatment plans. By highlighting active regions during specific activities, functional imaging helps in studying conditions like Alzheimer's disease, epilepsy, and depression, enhancing our knowledge of the human brain.