When you need to coordinate multiple animations or create complex sequences, nesting timelines in GSAP can help you organize your code and manage playback more easily. Nested timelines allow you to group related animations—such as animating a set of elements together—so you can control them as a single unit within a larger animation flow. This is especially useful for interfaces with repeating animation patterns, modular components, or when you want to reuse animation logic in multiple places.

With nested timelines, you can pause, play, reverse, or seek to specific points in your animation structure, giving you precise control over how and when animations run. For example, you might use a nested timeline for a modal's entrance and exit animations, then include that timeline in a main sequence that also animates the background or other UI elements. This approach keeps your code modular and makes it easier to maintain and update complex animation flows.