A peace symbol is a representation or object that has come to symbolize peace.
Generic peace symbols
The dove and the olive branch
A white dove is generally a symbol for peace. This comes from an old biblical motif; a dove was supposed to have been released by Noah after the flood in order to find land; it came back carrying an olive branch, telling Noah that, somewhere, there was land.
"The 70's" peace symbol
The peace symbol (☮) was designed and completed February 21 1958 by Gerald Holtom , a commercial artist in Britain.
Holtom had been commissioned by the Campaign for Nuclear Disarmament to design a symbol for use at an Easter march to Canterbury Cathedral in protest against the Atomic Weapons Research Establishment at Aldermaston in England.
The peace symbol was popularized in America by such pacifist figures as Albert Bigelow.
The symbol itself is a combination of the semaphore signals for the letters "N" and "D", standing for Nuclear Disarmament. (The letter "N" is two flags held in an upside-down "V", and the letter "D" is one flag pointed straight up and the other pointed straight down).
In Unicode, the peace symbol is U+262E, and can thus be generated in HTML by typing ☮ or ☮. However, many browsers will not have a font that can display it.
The fact that symbol resembles a bird's foot in a circle gave rise to alternative interpretations, ranging from plain mockery of "crow's foot" and "American Chicken" (a right wing hint that peace is for cowards) to a number of occult meanings from conspiracy theorists, since a crow or a raven is a gloomy bird in various mythologies.
Furthermore, the far-right John Birch Society has referred to it as a "broken cross" – accusing the peace movement of repudiating Christ. It has also been called a relative of the Nazi swastika – or the rune algiz inverted, said to mean "hidden danger". It resembles the rune calc.
Unique peace symbols
Some unique items, often monuments, have come to symbolize peace. For example, the Japanese Peace Bell was a gift from the UN Association of Japan to the United Nations, presented to them in 1954. The bell remains at UN headquarters and is struck yearly, in remembrance for peace.