Water hardness refers to the concentration of minerals, primarily calcium and magnesium, in water. These minerals dissolve in water as it moves through soil and rocks, leading to varying levels of hardness. Water hardness is typically measured in parts per million (ppm) or degrees of hardness. Hard water can cause issues such as scale buildup in pipes and appliances, reducing their efficiency. It may also affect soap and detergent performance, making it harder to create lather. Understanding water hardness is important for both household and industrial applications to ensure proper maintenance and usage.