Most natural movements follow a curved path rather than a straight line. If you throw a ball or even watch how your hand moves when you wave, the trajectory is usually an arc. Animators observed that perfectly straight motions look unnatural, so they introduced the principle of the arc: virtually any action, from a character’s arm swing to a head turn, will have a slight circular motion to it for realism.

   When it comes to UI animation, using arcs means moving elements along curved paths to create more organic transitions. While our screens are flat and coordinates are often defined in straight X/Y axes, a touch of curvature in movement can make a big difference.

   A secondary action in animation is a supporting motion that complements the main action, adding more dimension and interest. For instance, if a character is walking (primary action), their coat might be swaying or their head might be bobbing (secondary actions). These extra movements enrich the scene without stealing focus from the primary motion. The important thing is that the secondary action enhances the main action’s narrative or feeling – it shouldn’t distract or confuse, but rather make the whole animation more convincing and engaging.

   In UI/UX, secondary actions are like the little delights or informative cues that accompany a primary interaction. They are often subtle animations that play alongside the main effect to reinforce feedback or add personality.

   Timing in the context of animation refers to the speed and rhythm of an action, which is determined by the number of frames or how long an action takes. In classical animation, timing can convey different emotions or even physical laws – a heavy object moves slowly (more frames, slower timing), whereas a quick sharp movement (fewer frames) feels snappy and light. Good timing makes the difference between a sluggish motion and a crisp one, or between natural and awkward. It also affects mood: comedic actions often have punchy timing, while serious actions might be more measured.

   In UI/UX design, timing is critical for both aesthetics and usability. It determines how responsive the interface feels.

   Exaggeration is a hallmark of Disney-style animation – it’s about pushing movements or characteristics beyond realistic limits to emphasize a point. If a character is surprised, their jaw might literally drop to the floor in a cartoon – clearly not realistic, but it communicates the feeling in a dramatic, humorous way. Exaggeration doesn’t always mean cartoonish physics; it can be more subtle, like making a sad character’s slump just a bit deeper, or a fast punch even quicker and more forceful than it would be in reality. The idea is to avoid dull or “too perfect” realism and instead create a more expressive and clear action by amplifying it.

   In UI animation, we use exaggeration to ensure users notice and understand feedback, or to add a layer of fun and emphasis to interactions. Interfaces are generally functional, but a touch of exaggeration can make an interaction memorable.

   In its original context, solid drawing refers to the classical animation principle that animators should draw characters and objects with a sense of three-dimensionality, weight, and balance. Even though the artwork is 2D, it should feel like there’s volume, avoiding flat or inconsistent drawings that break the illusion of life. Essentially, it’s about having strong fundamentals in form and anatomy so the animated world feels consistent and believable.

   When we bring this concept to UI/UX design, it’s less about literal drawing skills and more about the visual and spatial coherence of our elements. You might think of it as making sure your UI elements feel “solid” and grounded, not floaty or confusing.

   The last principle, appeal, is somewhat abstract but incredibly important. In traditional animation, appeal is about creating characters, objects, or even motions that are attractive and engaging to the audience. It doesn’t necessarily mean cute or pretty – a villain can have appeal in how interesting they look. It’s about charisma and visual charm. Walt Disney and his animators believed every character should have appeal, whether heroic, evil, or comic, to hold the audience’s interest. In other words, something about the design and animation should captivate people, be it through likability, style, or uniqueness.

   In the context of UI/UX design, appeal translates to the overall charisma of your interface – the blend of visual design and motion that makes your product enticing and pleasant to use. It’s the difference between an app that feels generic or cold and one that feels inviting or even fun. Using animation with appeal means the animations not only serve a functional purpose (as many we discussed do) but also contribute to a distinctive personality of the interface. Think of the little delightful touches in a modern app that make you smile: perhaps a witty loading animation, or an onboarding sequence with charming illustrations that animate, or a mascot character that guides you through a tutorial. These are elements aimed at creating an emotional connection with the user.

Disney’s 12 Principles of Animation offer a powerful framework for crafting motion in digital design. From arcs and timing to exaggeration and appeal, these timeless techniques help designers create interfaces that are not only usable but delightful. By applying these principles to your UI/UX work, you can create experiences that feel smoother, more responsive, and deeply human.

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