An fMRI is a type of MRI uses to measure small changes in blood flow in the brain. It allows a doctor or researcher to see where brain activity happens when you do certain tasks.
fMRI can be used to plan brain surgery and other procedures, as it can tell a surgeon what areas of the brain to avoid during surgery. It can also be used in research.
On the day of your fMRI you'll need to avoid caffeine and remove any jewelry, accessories, piercings, or clothing that contain any sort of metal. Your doctor will give you any other specific instructions based on your circumstances.