The Animation interface of the Web Animations API represents
single animation player and provides playback controls and a
for an animation node or source.

The AnimationEffect interface of the Web Animations API defines
and future animation effects like `web.animation.KeyframeEffect`,
can be passed to `web.animation.Animation` objects for playing,
`KeyframeEffectReadOnly` (which is used by CSS Animations and

The AnimationEvent interface represents events providing information
to animations.

The AnimationPlaybackEvent interface of the Web Animations API
animation events.

The AnimationTimeline interface of the Web Animations API represents
timeline of an animation. This interface exists to define timeline
(inherited by `web.animation.DocumentTimeline` and future timeline
and is not itself directly used by developers. Anywhere you see
you should use DocumentTimeline or any other timeline type instead.

web.animation interfaces.

The DocumentTimeline interface of the the Web Animations API
animation timelines, including the default document timeline
via `Document.timeline`).

The EffectTiming dictionary, part of the Web Animations API,
used by `Element.animate()`, `KeyframeEffectReadOnly()`, and
to describe timing properties for animation effects. These properties
all optional, although without setting a duration the animation
not play.

The KeyframeEffect interface of the Web Animations API lets us
sets of animatable properties and values, called keyframes. These
then be played using the `Animation()` constructor.