What led to the switch?

Use APA style and formatting to compose the 1000-1500-words .Please find an example of a country currently using another country’s currency as its official denomination. Research this topic and answer the following questions, utilizing at least 5 (five) external references (recent academic or news articles) to back up your opinions and build your arguments:
Why would a country decide to use another country’s money as it is official currency? What are the advantages of this practice?
What are the disadvantages of this practice? 
Provide an example of a country that uses a foreign currency as its official monetary denomination.