The RBA changes the cash rate target based on a range of factors including inflation, the performance of the Aussie dollar, unemployment, the housing market, and Australia's Gross Domestic Product (GDP).
For example, if inflation rises above the target rate it means that Australians are spending their money too freely and prices are increasing too rapidly. But if the RBA raises interest rates to make it more expensive to borrow money, the economy will settle and price increases will slow down.
Conversely, the RBA will drop interest rates if inflation is too low and the economy is stagnating, encouraging more Australians to spend more money and stimulate economic growth.