The SI (International System of Units) is a standardized system used worldwide for measuring physical quantities. It provides a consistent framework for units such as length, mass, time, and temperature, making scientific communication clearer and more precise. The base units include the meter (m) for length, kilogram (kg) for mass, second (s) for time, and kelvin (K) for temperature. Established in 1960, the SI system is maintained by the International Bureau of Weights and Measures (BIPM). It has been adopted by most countries, facilitating international collaboration in science, industry, and trade. The SI system also includes derived units, which are combinations of base units, to measure other quantities like speed and energy.