Why Flutter animations need a vsync/TickerProvider

An article about Ticker and TickerProvider

If you have used Flutter animations before, you likely came across a parameter named vsync or the mixin SingleTickerProviderStateMixin.
But we are rarely using them ourselves. So what do they even do?

The difference between a "factory constructor" and a "static method"

If you’ve used Dart before, chances are that you’ve heard about the factory keyword.