Currency internalization is a situation where a country used it own currency outside of its own boarder for transaction.
Not many country currency is well accepted like this, currency internalization can occur when country that that involve in selling are interested in the buyer currency.
Countries like the United state of America, has the widest range of accepted currency across the world.
There is no place where the dollars is not accepted in the entire world.
There are many leading currency in the world that are well accepted after us dollars
Great Britain pounds
Euro
Dinnar
Canadian dollars
etc.