One cup contains 8 fluid ounces. The measurement of 1 cup is defined as a unit of capacity equal to 8 fluid ounces (237 milliliters), 16 tablespoons or 1 half-pint.
A cup is a measurement of volume which is why it is defined as equivalent to 8 fluid ounces, or 8 ounces of liquid. Dry materials can also be measured using cup units. In baking, for example, flour and sugar are frequently measured in cups.
A measuring cup is a physical container meant to hold 8 ounces. It is usually clear, and smaller units of measurement are marked on the outside using markers, including 1/2 cup, 1/3 cup and 1/4 cup.