Track animators animate to a specific target value over a fixed duration.

The ...Back parameters implicitly create a backwards timeline. The second timeline has it's own duration, and all properties and then specified in that timeline. This backwards timeline is for all of the animators, not just the ones with a ...Back property specified. This is important for understanding how the timing works in complex scenarios.

Tracks can be a continuous (like a floating point value), discrete (like an enum value), or a spline track. This is specified implicitly based on the properties used. Note that some properties only have effects with certain track types.