Alpha sizing is a method used in clothing and apparel design to categorize sizes based on a simple letter system, typically using letters like S (small), M (medium), L (large), and XL (extra-large). This system helps consumers quickly identify their size without needing to understand complex numerical measurements. The alpha sizing system is popular because it simplifies the shopping experience, making it easier for people to find clothes that fit well. However, it can vary between brands, so a size M in one brand may not be the same as a size M in another, leading to potential confusion for shoppers.