The celebration of the birth of Jesus Christ is (arguably) the most important Christian festival. Some would say Easter is equally important but, either way, Christmas is deeply significant.
It is also a festival for those who put no weight on Christianity (if you hadn't noticed).
What does it mean for Christians?
The Salvation Army says: "This year has been filled with uncertainty, anxiety and unexpected change. The good news of Christmas is that even when our celebrations may look different this year than in the past - the message of Christmas is timeless.
"Because Christmas is about the birth of God's son - Jesus. It is about how he came to give us love, hope and joy. That message doesn't change from year to year. In a year of so much bad news and devastation, this is good news worth celebrating."
So where does the tree fit in?
It came from Germany via Britain - and probably from pagans. The Romans, Druids and Vikings in their different parts of Europe decorated their temples with evergreen boughs in the depths of winter.
The tree took off in Britain when Queen Victoria was depicted with one, probably imported as an idea by her German husband.
If it was good enough for the Queen, it was good enough for her subjects.
Australians have adapted it to use "Christmas Bush", a native tree with white flowers which turn a deep red, ideally by Christmas.
Reindeer or kangaroos for Santa?
Kangaroos of course. Who ever heard of reindeer in Australia.
And this may jog a memory: Six white boomers, snow white boomers,
Racing Santa Claus through the blazing sun.
Six white boomers, snow white boomers,
On his Australian run.
The disgraced singer was recently released from one of Her Majesty's prisons in Britain but the song may still kindle a memory.
Turkeys came from America via Britain.
They are native to North America but were imported to Britain when the British colonists took over.
According to Good Housekeeping: "it was explorer William Strickland who brought back the birds from the New World (to Britain) in the mid-1500s, and King Henry VIII was the first monarch to enjoy eating them."
Turkey is the traditional Christmas meat - but we don't actually eat it very much.
According to market research company, Roy Morgan, one in eight Australians eat turkey around Christmas (which is far and away the peak of turkey consumption).
Turkeys as the Christmas ritual - but forget about them for the rest of the year, is the gist of it.
Australia's top scientific body - CSIRO - advises that a fridge should be around 5C and kept for "important food" like turkey ("Put stuff like drinks in the old fridge in the shed or on ice in an esky).
"If you're buying it frozen to cook at home, defrost it in the fridge for two days - longer if it's a big bird. Store it (and other raw meat) at the bottom of your fridge, and cooked meat and other ready to eat foods at the top so that any germs that drip off the raw meat don't contaminate other foods. Fruit and veggies in the bottom crisper should be protected from any drips."
Another turkey ritual
CSIRO says: "we love it on fresh bread with apple and watercress, or brie and beetroot".
In Britain, some families eat turkey on Christmas Day so they can have turkey sandwiches with crisps on Boxing Day.
It's the only day on which crisps are legitimate.