The new US hundred dollar bill, unveiled on April 21, includes many improved security features. "As with previous US currency redesigns, this note incorporates the best technology available to ensure we're staying ahead of counterfeiters," Treasury Secretary Timothy Geithner says in a statement.
Several Hong Kong dollars are displayed on the day of their release in September 2002, following eight years in which the denomination was only available as a coin. The bill's abstract geometric design is intended to reference architecture in the city according to the Hong Kong Monetary Authority. Peter Parks/AFP/FILE
The South African 10 Rand banknote features a rhinoceros on the obverse and a ram on the reverse. Currently, the 10, 20, 50, 100 and 200 rand notes each feature one of the 'Big Five' wildlife species, historically the most difficult animals in Africa to hunt. Newscom/FILE
The Dutch guilder was retired in 2002, when it was replaced by the Euro. The striking, yellow 50 guilder note features a sunflower prominently.
The Cook Islands dollar, still in circulation but no longer issued, is the currency of the Cook Islands, east of New Zealand.
The colorful Canadian $50 bill features a portrait of the country's 10th Prime Minister, William Lyon Mackenzie King.
The Australian dollar is the sixth most popular currency in the world. Most denominations of the colorful notes feature important historical Australians. The $5 bill features England's Queen Elizabeth II. Newscom/FILE
The Swiss franc, the only European franc not to have been replaced by the Euro, is used in Switzerland and Liechtenstein. The 100 franc note features Alberto Giacometti, a 20th century Swiss artist. Newscom/FILE
The Netherlands Antillean guilder is the official currency of the Netherlands Antilles, two groups of islands in the Caribbean Sea, and formerly in Aruba. Their 10 guilder bill depicts a hummingbird on geometric patterns.
The Icelandic krona is the official currency of Iceland. Their 100 krona note depicts 18th century Icelandic scholar Arni Magnusson. Due to the 2008/2009 financial crisis, the krona has fallen sharply against the dollar precipitating cries for adoption of the Euro in Iceland.
The Comorian franc is the official currency of the island nation of Comoros. The 2,000 franc note features a striking use of color and geometric pattern and includes images of a market scene, a mosque, and village huts on the island.
The massive US public auction of bitcoins – a first for the US government – had little effect on the price of bitcoin, which plunged after China's central bank refused to recognize the virtual online currency in December.