Australian Domain Name Registration will be:

• .com.au or .net.au for Australian commercial company
• .asn.au  for an Association
• .org.au for organizations
• .id.au is for individuals. 

Currently there are many types of Top Level domains to register and these vary by the last letters after the 'dot'.

• .com is the most common
• .net is used for a network
• .org originally for organization
• .biz is for business sites
• .info is for information sites