The primary system of measurement used in most parts of the world is the metric system. This system is based on units of ten, making calculations and conversions straightforward. The metric system includes units such as meters for length, liters for volume, and grams for mass. It is used in scientific research, international trade, and everyday life in nearly every country except for a few like the United States, where the imperial system is still prevalent. The metric system's simplicity and ease of use promote global consistency and communication in various fields, including science, engineering, and healthcare.