It was first manufactured in 1932 in Slough, England, by Forrest Mars Sr.[2] The bar consists of caramel and nougat coated with milk chocolate.

An American version of the Mars bar was produced with nougat and toasted almonds covered in milk chocolate, and later[when?]

The American version was discontinued in 2002, then revived in a slightly different form the following year under the name "Snickers Almond".

With minor variations, this version is sold worldwide, except for the US, and is packaged in a black wrapper with red gold-edged lettering.

[16][17] The European or Canadian version of the Mars bar is sold in some American grocery stores that stock imported food products.

The Original Mars bar in "Believe" packaging was sold in the UK from 18 April 2006 until the end of the 2006 FIFA World Cup in July.

"Believe" took prominence on the packaging ("Original Mars" appeared in smaller print) to indicate support for the England national football team.

[21] On 30 July 2008, the Tasmanian government announced that it had secured a major sponsor, Mars for a bid to enter the Australian Football League in a deal worth $4 million over 3 years and will temporarily change the name of its top-selling chocolate bar in Australia to Believe, to help promote Tasmania's cause.

[23] In 2010, to promote England's involvement in the 2010 FIFA World Cup, the background of the UK Mars packaging became the St. George cross.

First reports of Mars bars coated with batter and deep-fried being sold in Stonehaven, Scotland[26][27] date back to 1995.

[30] In Kathmandu, Nepal, momo dumplings in tourist areas have used Mars bars as an unusual filling.

The precautionary recall was issued after a customer found pieces of plastic in a Snickers bar purchased in Germany.

[40] It has been observed on several occasions that the price of a Mars bar correlates fairly accurately with the change in value of the pound sterling since World War II, much in the way that the Big Mac Index has proven to be a good indicator of the actual relative purchasing power of world currencies.

[41] Northern Irish pop-punk band The Undertones wrote and recorded a song called "Mars Bars", released as a B-side in 1979.