Liquid and powder detergents, both commonly used for laundry, differ mainly in their form, cost, efficiency, and storage requirements. Liquid detergents come in a form that is readily soluble in water, making them an effective choice for cold water washing. They are particularly well-suited to pre-treating spots and stains on fabrics, as the liquid can be applied directly to the affected area, ensuring a concentrated attack on the stain. Powder detergents, on the other hand, tend to be less expensive per load than liquid detergents. They also have a longer shelf life, as they are less likely than liquid detergents to lose their effectiveness over time. However, powder detergents can sometimes leave white residue on clothes if they do not dissolve completely, especially in cold water.