investors search for high yielding currencies.
aud is one such currency as it offers a better interest rate than other major countries
when people are in a good mood or are confident of future prospects, they are open to investing and taking risks (increased risk appetite). in this condition, they go invest/put their money in currencies (like AUD), stocks, commodities, and others.
yes, it is also tied up with economies and commodities.
Australia is 1 of the stronger and more stable economies right now, buoyed by the demand for commodities which Australia is rich in.
buying a currency such as AUD is a vote of confidence in that currency's country/economy.
when you study and trade currencies, you are basically trading a highly interrelated market so it pays to learn about these various intertwined aspects. you have an enquiring mind and that is truly awesome