A T-shirt, or tee shirt, is a style of fabric shirt named after the T shape of its body and sleeves. Traditionally it has short sleeves and a round neckline, known as a crew neck, which lacks a collar. T-shirts are generally made of a stretchy, light and inexpensive fabric and are easy to clean.

Typically made of cotton textile in a stockinette or jersey knit, it has a distinctively pliable texture compared to shirts made of woven cloth. Some modern versions have a body made from a continuously knitted tube, produced on a circular knitting machine, such that the torso has no side seams. The manufacture of T-shirts has become highly automated and may include cutting fabric with a laser or a water jet.

The T-shirt evolved from undergarments used in the 19th century and, in the mid-20th century, transitioned from undergarment to general-use casual clothing.

A V-neck T-shirt has a V-shaped neckline, as opposed to the round neckline of the more common crew neck shirt (also called a U-neck). V-necks were introduced so that the neckline of the shirt does not show when worn beneath an outer shirt, as would that of a crew neck shirt.