Mass density, a crucial property of materials, is the mass per unit volume. Brass, an alloy primarily composed of copper and zinc, has a density that depends on the ratio of these metals. Yellow brass, with a higher copper content, is denser than red brass with more zinc. Impurities and additives can also affect brass density. Density measurement techniques include Archimedes’ principle, pycnometry, X-ray diffraction, and specific gravity. The applications of brass, spanning across various industries, are driven by its durability, corrosion resistance, and aesthetic appeal.