Measurement units are standardized quantities used to express physical properties, such as length, mass, and volume. Common units include meters for length, kilograms for mass, and liters for volume. These units allow for consistent communication and comparison of measurements across different contexts and disciplines. There are two main systems of measurement: the Imperial system, used primarily in the United States, and the Metric system, which is widely adopted around the world. The Metric system is based on multiples of ten, making calculations easier, while the Imperial system includes units like inches and pounds, which can be less intuitive.