A prison uniform is any uniform

Uniform

A uniform is a set of standard clothing worn by members of an organization while participating in that organization's activity. Modern uniforms are worn by armed forces and paramilitary organizations such as police, emergency services, security guards, in some workplaces and schools and by inmates...

 worn by individuals incarcerated in a prison

Prison

A prison is a place in which people are physically confined and, usually, deprived of a range of personal freedoms. Imprisonment or incarceration is a legal penalty that may be imposed by the state for the commission of a crime...

, jail

Jail

A jail is a short-term detention facility in the United States and Canada.Jail may also refer to:In entertainment:*Jail , a 1966 Malayalam movie*Jail , a 2009 Bollywood movie...

 or similar facility of detention

Detention (imprisonment)

Detention is the process when a state, government or citizen lawfully holds a person by removing their freedom of liberty at that time. This can be due to criminal charges being raised against the individual as part of a prosecution or to protect a person or property...

.
During the Nazi period

Nazi Germany

Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 of Germany, interned people in the concentration camp system were often made to wear prisoner's uniforms.
In the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, prison uniforms formerly consisted of a white jacket

Jacket

A jacket is a hip- or waist-length garment for the upper body. A jacket typically has sleeves, and fastens in the front. A jacket is generally lighter, tighter-fitting, and less insulating than a coat, which is outerwear...

, trousers

Trousers

Trousers are an item of clothing worn on the lower part of the body from the waist to the ankles, covering both legs separately...

 and pillbox hat

Pillbox hat

A pillbox hat is a small woman's hat with a flat crown and straight, upright sides, and no brim.-History:Historically, the pillbox was also military headgear, often including a chin strap, and can still be seen on ceremonial occasions in some countries, especially former members of the Commonwealth...

, all stamped with the broad arrow

Broad arrow

A broad arrow or pheon is a type of arrow with a typically flat barbed head. It is a symbol used traditionally in heraldry, most notably in England, and later the United Kingdom to mark government property.-Use in heraldry:...

 to denote crown property.

The idea of covering the uniforms of Penal Servitude prisoners with the broad arrow

Broad arrow

A broad arrow or pheon is a type of arrow with a typically flat barbed head. It is a symbol used traditionally in heraldry, most notably in England, and later the United Kingdom to mark government property.-Use in heraldry:...

 was first introduced by Sir Edmund Du Cane in the 1870s after his appointment as Chairman of Convict Directors and Surveyor-General of prisons.