The mens t shirt was originally created to serve as an undergarment, but they have evolved into so much more. There are still simple, white men's shirts as undergarments, but they are more frequently worn as the main piece. Cool men's t-shirts are used as mediums for expression today, as well, or as advertising or even art. Some cool men's t-shirts have photos on them, or slogans, or just popular catchphrases of the day. There are men's shirts with political statements, which can sometimes be offensive, and there are men's shirts that are intentionally offensive just for the sake of grabbing attention.

A mens' t shirt can be purely decorative and nice enough to wear to an office job, or it can be completely casual and better-suited for a construction job. A mens t shirt typically extends to the waist, although one fashion is for oversized men's shirts, namely in modern hip hop fashion. A more recent trend in cool men's t-shirts in cold weather is wearing a long-sleeved thermal t-shirt, and then putting a short sleeved t-shirt of a different color over the long sleeved shirt. This is known as layering. Variants of the mens t-shirt, such as the a-shirt (with the nickname "wife beater") and the muscle shirt eventually came into fashion, as well, and these are often imprinted with different graphics and slogans, as well.