human
How can I tell if a t-shirt is made of cotton or polyester?
assistant
Cotton and polyester are both synthetic materials, but they have different properties. Polyester is usually more durable than cotton, so it's often used in clothing that needs to be washed frequently. Cotton is softer and more comfortable against the skin, but it doesn't hold up as well when exposed to moisture. If you're looking for a shirt that will last longer and still feel soft, then cotton might be the better choice.