T-shirts are also called T-shirts. At first it was underwear, but it was actually a shirt with a lapel collar and a half open collar. Later developed into outerwear, including two series of T-shirts, singlets and T-shirts. There are different opinions on the origin of the name of the T-shirt. One theory is that the dockers who unloaded tea in Annapolis, Maryland, USA in the 17th century wore this short-sleeved shirt. People abbreviate "tea" as "T". This shirt is called T-Shirt, or T-Shirt; the second theory is that in the 17th century, British sailors were ordered to add short sleeves to the vest to cover the armpit hair to avoid unsightly; there is also a theory that its sleeves and upper body form a "T" shape, that is, its clothes are a T-shaped stitched collar, hence the name.