The parts of the Australian National Flag mean the following:
The Union Jack in the upper left corner (or canton) acknowledges
Australia's origin as a British settlement.
The Southern Cross, positioned on the right hand side of the flag,
is a constellation visible from all of Australia's states and
territories, and which was vital to early ships' navigation, and
which represents Australia's position in the Southern Hemisphere.
In the bottom left hand corner is the Federation Star, also known
as the Commonwealth Star, a seven pointed star which represents the
union of the six colonies at federation. There is a seventh point
to represent Australia's many territories (mainland and offshore).
These symbols are on a British blue ensign.