When you animate elements with Anime.js, the easing type you select dramatically changes how the motion feels to the user. Using a built-in easing like easeInOutQuad creates a smooth, predictable acceleration and deceleration, making the movement feel even and polished. This is a good choice for general UI transitions where you want the animation to feel natural but not distracting.

Spring easing, such as spring(1, 80, 10, 0), adds a bouncy, physics-inspired motion. The element overshoots and settles, which can make the animation feel playful or lively. Use spring easing when you want to draw extra attention to an interaction or mimic real-world movement, like objects bouncing into place.

Custom bezier easing, like cubicBezier(.5,1.5,.5,-0.5), lets you create unique motion curves. This gives you full control over the timing and feel of the animation, allowing for exaggerated or stylized effects. Custom bezier curves are best when you need a very specific motion or want to match branding guidelines.

Choosing the right easing depends on your animation goals: use built-in easings for subtlety and consistency, spring for dynamic and engaging motion, and custom bezier for creative or branded effects.