In addition to the US, other countries that use the US Dollar (USD) as their official currency include East Timor, Ecuador, El Salvador and Panama. Countries do not have to get permission to use another country’s currency as their own, and they might use foreign currency if its value is more stable. "Reserve currency" is a term that refers to foreign currency that is used to set domestic exchange rates or to pay off international debt. The US Dollar is the world’s most dominant reserve currency, according to 2013 estimates, and this is thought to be a reason that foreign countries adopt it instead of other currencies.
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