Animation timeline is where you test your animations. You can move the time to any point of the animation and see how precisely the component looks, immediately in the preview. You can also let it play indefinitely, which is useful to test the animations that repeat multiple times or never end.
Animation timeline has 3 main parts - The components, the draggable properties, and the animation controls.
The component part of the animation timeline presents you a list of components (and groups, and properties) that participate in the single animation. Each animation can have multiple components, and multiple properties, but it can only have one component that invokes it (more on that in the Chaining section).
The draggable properties
Every property that you animate on the component will show up in the middle area, that is scrollable and where you can drag them left or right, or rescale them. This gives you quick access to the timing aspects of the animation, down to the last property.
The animation controls
The animation controls give you overview of the state of the animation, and also quick access to play, replay and stop / pause functionality. The red line above the properties marks the time in which the animation currently is.