It’s true that sweatshirts are great at keeping wearers warm, but as they were typically cotton practice jerseys back in the day, the ‘sweat’ part of the word comes from their origins on the field. So, what is a sweatshirt used for today? Sweatshirts are still used for their original purpose as comfortable athletic wear, but they are also worn for staying warm in cooler temps, repping a collegiate team, or layering to form a fashionable outfit.