The US gallon is a unit of volume commonly used in the United States, primarily for measuring liquids. It is defined as equal to 128 fluid ounces, or approximately 3.785 liters. The US gallon is part of the US customary system of measurement, which is different from the metric system used in most other countries. In contrast, the imperial gallon, used in the United Kingdom and some other countries, is larger, measuring about 4.546 liters. Understanding the difference between these two types of gallons is important for accurate measurements in cooking, fuel consumption, and other applications.