The RBA is Australia's central bank. The RBA is responsible for making monetary policy decisions, including setting the cash rate, announced on the first Tuesday of every month (except January).
Depending on a range of domestic and global factors, the cash rate may change often, or remain the same for an extended period. In this case, rates have not increased for almost 12 years.
The RBA increases the cash rate to manage the performance of the Australian economy. One key factor they consider is the inflation rate. When inflation is on the way up, it means the cost of living goes up too and things are more expensive.
The price of food, materials and fuel has surged in recent months along with the rising cost of new dwelling purchases by owner-occupiers.