The T shirt evolved from undergarments used in the 19th century, through cutting the one-piece "union suit" underwear into separate top and bottom garments, with the top long enough to tuck under the waistband of the bottoms. T shirts, with and without buttons, were adopted by miners during the late 19th century as a convenient covering for hot environments.

T shirts, as a slip-on garment without buttons, originally became popular in the United States when they were issued by the U.S. Navy during or following the Spanish American War. These were a crew-necked, short-sleeved, white cotton undershirt to be worn under a uniform. It became common for sailors and Marines in work parties, the early submarines, and tropical climates to remove their uniform "jacket", wearing (and soiling) only the undershirt. It is possible that the Navy uniform boards first discovered the T shirt by watching dock crews.

Named the T shirt due to the shape of the garment's outline, they soon became popular as a bottom layer of clothing for workers in various industries, including agriculture. The T shirt was easily fitted, easily cleaned, and inexpensive, and for this reason it became the shirt of choice for young boys. Boys' shirts were made in various colors and patterns.

By the time of the Great Depression, the T shirt was often the default garment to be worn when doing farm or ranch chores, as well as other times when modesty called for a torso covering but conditions called for lightweight fabrics.

Following World War II, it became common to see veterans wearing their uniform trousers with their T shirts as casual clothing, and they became even more popular after Marlon Brando wore one in A Streetcar Named Desire, finally achieving status as fashionable, stand-alone, outer-wear garments.

Beginning in the late 1960s, the T shirt became a medium for wearable art. Psychedelic art poster designer Warren Dayton pioneered several political, protest, and pop-culture art T shirts featuring images of Cesar Chavez, political cartoons, and other cultural icons in an article in the Los Angeles Times magazine in late 1969. Today, many notable and memorable T shirts produced in the 1970s have now become ensconced in pop culture.

Examples include the bright yellow happy face T shirts, The Rolling Stones tops with their "tongue and lips logo, and the iconic "I ♥ N Y”.

They can also be used to carry commercial advertising, souvenir messages, and protest art messages.
Large Bales of Printed T-Shirts
    
Trendy

T shirts were originally worn as undershirts. Now T shirts are worn frequently as the only piece of clothing on the top half of the body, other than possibly a bra or an undershirt (vest). T shirtshave also become a medium for self-expression and advertising, with any imaginable combination of words, art, and even photographs on display.

A T shirt typically extends to the waist. Variants of the T shirt, like the tank top, crew neck, A-shirt (with the nickname "wife beater"), muscle shirt, scoop neck, and V-neck have been developed. Hip hop fashion calls for "tall-T" T shirts which may extend down to the knees. A 1990s trend in women's clothing involved tight-fitting "cropped" T shirts short enough to reveal the midriff. Another popular trend is wearing a short-sleeved T shirt of a contrasting color over a long-sleeved T shirt. This is known as "layering".

    
Branding

In the early 1950s several companies based in Miami, Florida, started to brand T shirts with different resort names and various characters. The first company was Tropix Togs, under founder Sam Kantor, in Miami. They were the original license for Walt Disney characters that included Mickey Mouse and Davy Crockett. Later, other companies expanded into the T shirt printing business, including Sherry Manufacturing Company, also based in Miami. Sherry started in 1948 by its owner and founder Quinton Sandler as a screen print scarf business and evolved into one of the largest screen printed resort and licensed T shirts companies in the United States.

In 1959, plastisol, a more durable and stretchable ink, was invented, allowing much more variety in T shirt designs.

In the 1960s, the ringer T shirt appeared and became a staple fashion for youth and rock-n-rollers. The decade also saw the emergence of tie-dyeing and screen printing on the basic T shirt. In the late 1960s Richard Elman, Robert Tree, Bill Kelly, and Stanley Mouse set up the Monster Company in Mill Valley, California, to produce fine art designs expressly for T shirts. Monster T shirts often feature emblems and motifs associated with the Grateful Dead and marijuana culture.Additionally, one of the most popular symbols to emerge out of the political turmoil of 1960s were T shirts bearing the face of Marxist revolutionary Che Guevara.

The most common form of commercial T shirt decoration is screen printing. In screen printing, a design is separated into individual colors. Plastisol or water based inks are applied to the shirt through mesh screens which limits the areas where ink is deposited. In most commercial T shirt printing, the specific colors in the design are used. To achieve a wider color spectrum with a limited number of colors, process printing (using only cyan, magenta, yellow and black ink) or simulated process (using only white, black, red, green, blue, and gold ink) is effective. Process printing is best suited for light colored shirts. Simulated process is best suited for dark colored shirts. Very few companies continue to use water-based inks on their shirts. The majority of other companies that create shirts prefer to use plastisol due to the ability to print on varying colors without the need for color adjustment at the art level.

Specialty inks trend in and out of fashion and include shimmer, puff, discharge, and chino based inks. A metallic foil can be heat pressed and stamped onto any plastisol ink. When combined with shimmer ink, metallic’s give a mirror like effect wherever the previously screened plastisol ink was applied. Specialty inks are more expensive to purchase as well as screen and tend to appear on garments in boutiques.

Other methods of decoration used on T shirts include airbrush, applique, embroidery, impressing or embossing, and the ironing on of flock lettering, heat transfers, or dye-sublimation transfers. Laser printers are capable of printing on plain paper using a special toner containing sublimation dyes which can then be permanently heat-transferred to T shirts.

In the 1980s, thermo chromatic dyes were used to produce T shirts that changed color when subjected to heat. The Global Hypercolour brand of these was a common sight on the streets of the UK for a few years, but has since mostly disappeared. These were also very popular in the United States among teenagers in the late 1980s. A downside of color-change garments is that the dyes can easily be damaged, especially by washing in warm water, or dye other clothes during washing.

At the turn of the 21st century, designing custom T shirts online became more popular. Popular websites began to use digital printing (such as Direct to Garment or DTG printing) to allow customers to design their own T shirts online with no minimum orders. In the beginning, DTG could not print well on dark garments; however, with the help of some online T shirt retailers, printer manufacturers such as T-Jet have all but perfected the process, providing consumers with many more printing options.
    
    
Expressive messages

Since the 1980s, T shirts have flourished as a form of personal expression.

T shirts with bold slogans were popular in the UK in the 1980s.

Screen printed T shirts have been a standard form of marketing for major consumer products, such as Coca-Cola and Mickey Mouse, since the 1970s. However, since the 1990s, it has become common practice for companies of all sizes to produce T shirts with their corporate logos or messages as part of their overall advertising campaigns. Since the late 1980s and especially the 1990s, T shirts with prominent designer-name logos have become popular, especially with teenagers and young adults. These garments allow consumers to flaunt their taste for designer brands in an inexpensive way, in addition to being decorative. Examples of designer T shirt branding include Calvin Klein, FUBU, Ralph Lauren and The Gap. These examples also include representations of rock bands, among other obscure pop-culture references. Licensed T shirts are also extremely popular. Movie and TV T shirts can have images of the actors, logos, and funny quotes from the movie or TV show. Often, the most popular T shirts are those that characters wore in the film itself (e.g., Bubba Gump from Forrest Gump and Vote For Pedro from Napoleon Dynamite).

Designer Katharine Hamnett, in the early 1980s, pioneered outsize T shirts with large-print slogans. The early first decade of the 21st century saw the renewed popularity of T shirts with slogans and designs with a strong inclination to the humorous and/or ironic. The trend has only increased later in this decade, embraced by celebrities, such as Britney Spears and Paris Hilton, and reflected back on them, too ('Team Aniston').The political and social statements that T shirts often display have become, since the first decade of the 21st century, one of the reasons that they have so deeply permeated different levels of culture and society. The statements also may be found to be offensive, shocking, or pornographic to some. Many different organizations have caught on to the statement-making trend, including chain and independent stores, websites, and schools. A popular phrase on the front of T shirts demonstrating T shirts' popularity among tourists is the humorous phrase "I did _____ and all I got was this lousy T shirt." Examples include "My parents went to Las Vegas and all I got was this lousy T shirt." T shirt exchange is an activity where people trade their T shirts they are wearing. Some designs specifically write on the shirt "trade with me".