A raincoat is a waterproof or water-resistant garment worn on the upper body to shield the wearer from rain. The term rain jacket is sometimes used to refer to raincoats with long sleeves that are waist-length. A rain jacket may be combined with a pair of rain pants to make a rainsuit. Rain clothing may also be in one piece, like a boilersuit. Raincoats, like rain ponchos, offer the wearer hands-free protection from the rain and elements; unlike the umbrella.

Modern raincoats are often constructed from waterproof fabrics that are breathable, such as Gore-Tex or Tyvek and DWR-coated nylon. These fabrics and membranes allow water vapor to pass through, allowing the garment to 'breathe' so that the sweat of the wearer can escape. The amount of pouring rain a raincoat can handle is sometimes measured in the unit millimeters, water gauge.