What is Australia Day - and why is it controversial?

The 26th of January marks the day in 1788 when the First Fleet arrived in Sydney Cove, beginning the British colonisation of Australia.

People gathered for a night of reflection on the eve of Australia Day, at Barangaroo in Sydney. Source: AAP

Now commemorated with a public holiday, millions see it as a time to celebrate all that they love about being Australian.

But for many Aboriginal and Torres Strait Islanders, it's a day of pain.

Group of People Waving Australian Flags in Back Lit Source Source: iStockphoto

Across the country, tens of thousands of people spend the 26th of January participating in 'Invasion Day' events.