A T-shirt (or tee shirt) is a shirt, usually buttonless, collarless and pocketless, with a round neck and short sleeves, pulled on over the head. There are also long-sleeved T-shirt and sleeveless T-shirt variants.

T-shirts were originally worn as undershirts. This still occurs, but T-shirts are now also frequently worn as the only piece of clothing on the top half of the body (except that women usually wear a bra beneath it).

A T-shirt typically extends to the waist, although one fashion is for "oversized" T-shirts. A more recent trend in women's clothing involves tight-fitting "cropped" T-shirts that are short enough to reveal the lower abdomen including the belly button. T-shirt fashions include styles for men and women, and for all age groups, including baby, youth and adult sizes. T-shirts are often decorated with text and/or pictures.

T-shirts are manufactured by the textile industry. They are typically made of cotton or polyester fibers (or a mix of the two), knitted together in a jersey stitch that gives a T-shirt its distinctive soft texture.

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