The Polish flag that is used inland is a simple flag that consists of two horizontal stripes of red and white. There is an alternate flag displayed which is used abroad and at sea that features the Polish coat of arms, which is displayed here. It was adopted in 1919 and last modified in 1990.
The most strange part of the flag is the limited use of the two designs. When the flag is flown at/in Sejm, Senate, and many other government buildings, it must be flown without the coat of arms. However, if it is flown at an embassy, airport, or merchant ships, it must have the coat of arms.