1. CSS3 Transitions

    Simple method of animating certain properties of an element, with ability to define property, duration, delay and timing function.

  2. View Transitions API (single-document)

    Provides a mechanism for easily creating animated transitions between different DOM states, while also updating the DOM contents in a single step. This API is specific to single-document transitions, support for same-origin cross-document transitions is [being planned](https://github.com/WICG/view-transitions/blob/main/cross-doc-explainer.md).

  3. element api: `transitionstart` event