ABS Geographies

The ABS has a Statistical Geography standard, at which they release all of their data from the census. This is a very important hierarchy, and it is a good idea to become familiar with it.
2011ABS

  • As the finest level of spatial aggregation, meshblocks usually represent a city block, or a tall apartment block- say, 30 to 60 households, or about 100 people
  • SA1s are a small neighbourhood.
  • SA2s represent, as closely as possible, gazetted suburbs in a metropolitan region.
  • SA3s are similar in their boundaries to LGAs,
  • SA4s represent large regions, while
  • GCCSAs are Greater Capital City Statistical Areas and represent each major metropolitan area in the country.

NOTES:
Geographies such as postcodes and suburbs although commonly known, are not statistically rigorous.
Here is the pre-2011 geographic hierarchy – These have coverages like LGA, SLA, SSD, SD etc- you’ll see these codes in older datasets.

For (much) more information on ABS Geographies, please visit http://www.abs.gov.au/geography
See also ASGS 2011 Structure and Summary for a good notated diagram