The United States Dollar (USD) is the official currency of the United States, first issued in 1792. It is identified by the ISO 4217 code USD and is commonly represented by the symbol $. The authority for issuing US dollars lies with the United States Department of the Treasury. Currently, circulating US dollar banknotes include denominations of 1, 2, 5, 10, 20, 50, and 100 dollars, along with coins in denominations of 1, 5, 10, 25, 50 cents, and 1 dollar. The U.S. Dollar ranks first globally in terms of trading volume, comprising 88.3% of the total global foreign exchange transactions. Local money changers in Hong Kong all offer the buying and selling of U.S. Dollars.

The Australian Dollar (AUD) is the official currency of Australia, and it has been in circulation since 1966. It is represented by the ISO 4217 code AUD, and its symbol is commonly denoted as A$. The issuance and management of the Australian Dollar are the responsibility of the Commonwealth Government of Australia. Currently, there are banknotes in denominations of 5, 10, 20, 50, and 100 dollars, along with coins in values of 5, 10, 20, and 50 cents, as well as 1 and 2 dollars.The Australian Dollar ranks sixth globally in terms of trading volume, and the majority of money changers in Hong Kong support both buying and selling of the Australian Dollar.