Electricity in Australia is 220-240 volts AC. If you bring electrical appliances that happen to use 110 volts instead, directly plugging them into an Australian plug will burn them out. Transformers are therefore required, and these are probably best bought abroad.
A suitable transformer bought in Australia will cost around A$ 70.
Whether you need a transformer or not, make sure, that your appliances are configured for the three pin Australian plug. If you cannot get one of these abroad you may be wise to wait until you get to Australia.
If you have a laptop computer you will probably find that the transformer that comes with it automatically adjusts to 110 or 240 volts. Check though. If it is able to cope with both currents you will still need an adapter for the Australian three-pin system.
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