Version 12 continues expanding the support for real-world measurements in the system, something fundamental in science, engineering and many other areas of knowledge. New additions include better coverage of quantity variables and physical constants, extended ways of referring to calendar units of time and new functions to describe uncertainty in values and its propagation through computations. As the Wolfram Language expands into new domains of knowledge, seamless integration of these basic elements becomes essential, and combined with the power of the rest of the system, makes the Wolfram Language a very powerful tool to describe, measure and analyze the world around you.