What Is a Keyframe in Animation? A Clear Guide

The short answer

So what is a keyframe in animation? A keyframe is a single frame that marks an important moment in a motion — the start of a jump, the peak of a wave, the instant a door slams shut. You set the key poses, and everything between them is calculated or drawn to connect them. Think of keyframes as the milestones on a road trip: you decide the cities you'll stop in, and the highway fills in the miles.

That idea is the backbone of nearly every kind of animation, from hand-drawn cartoons to 3D films to the motion graphics scrolling past you online. Master it and you understand how almost all screen motion is built.

Where the idea came from

Keyframes started in traditional hand-drawn studios. A lead animator would draw the most important poses in a scene — the extremes of an action — and hand them off. These principal drawings were the "keys."

Junior artists, called inbetweeners, then drew the frames that bridged one key pose to the next. This split let the senior artist focus on performance and timing while the team handled the labor of filling in motion. The word "keyframe" is a direct inheritance from that workflow, and you can read more about its origins on Wikipedia.

The logic survived the jump to digital untouched. Whether you're drawing on paper or dragging sliders in software, you still define the important moments and let something else handle the gaps.

How keyframes work

In modern software, a keyframe records the state of a property at a specific point in time. Position, scale, rotation, opacity, color — almost anything measurable can be keyframed.

Here's the basic loop. You move the playhead to a moment on the timeline, set a value (say, an object at the left edge of the screen), and drop a keyframe. Then you move the playhead forward, change the value (the object at the right edge), and drop a second keyframe. The software now knows two states and the time between them.

From there it does the math. The gap gets filled automatically by a process called interpolation — the software generates every frame needed to travel from the first value to the second. That's how keyframes work at their core: you define the anchors, the computer connects them.

A few properties you'll keyframe constantly:

• Position — moving an object across the frame
• Scale — growing or shrinking
• Rotation — spinning or tilting
• Opacity — fading in and out

Keyframe vs tween: what's the difference

This is where beginners get tangled, so let's make it clean. A keyframe is a moment you define. A tween is what happens in the space between two keyframes.

"Tween" is short for "in-between," and tweening is the act of generating those connecting frames. In the keyframe vs tween relationship, keyframes are the decisions and tweens are the consequences. You can't have a tween without two keyframes bracketing it.

The practical upside is huge. Instead of drawing or placing all 24 frames of a one-second move, you set two keyframes and let the tween produce the other 22. That's the difference between hours of manual work and a few clicks.

Interpolation is the engine behind tweening, and it comes in flavors. Linear interpolation moves at a constant speed — mechanical and even. Eased interpolation (often Bézier) speeds up and slows down, which reads as far more natural because real objects accelerate and decelerate. A hold keeps a value locked with no motion until the next key.

What are in-between frames

In-between frames are the frames that live between your keyframes — the ones that carry the eye from one key pose to the next. In hand-drawn animation a person draws them; in digital animation the software tweens them. Same job, different labor.

The count of in-between frames controls timing. Few in-betweens between two poses means a fast, snappy move. Many in-betweens means a slow, drawn-out one. This is one of the most powerful levers in animation: the poses can be identical, but changing how many frames separate them completely changes the feel.

Spacing matters as much as count. Evenly spaced in-betweens feel robotic; in-betweens bunched near the keyframes (with more distance in the middle) create the acceleration that makes motion believable. This is the heart of the classic "ease in, ease out" principle, part of the long-standing 12 principles of animation.

Keyframe animation explained in practice

Let's put keyframe animation explained into a real example. Say you want a title card to slide up and settle into place.

You'd set a keyframe with the text below the frame and fully transparent. A second keyframe, a half-second later, puts it centered and fully visible. Add eased interpolation so it decelerates as it arrives, and you've got a clean, professional move from two decisions.

Want it to feel bouncier? Add a third keyframe just past the final position, then let it settle back. Now the title overshoots slightly and springs into place. Every refinement is just another key pose — the tweens update themselves.

This same thinking scales up. A character walk cycle is keyframes at the contact, down, passing, and up positions, with in-betweens filling the stride. A camera move is keyframes on the start and end framing. Once you see motion as key poses plus connective tissue, you can build almost anything.

Where keyframes meet AI video

Here's a shift worth understanding. Traditional keyframing asks you to set precise numeric values on a timeline. AI video generation approaches motion differently — you describe what should happen, and the model produces the frames, in-betweens and all.

That doesn't make keyframe thinking obsolete; it makes it more useful. Knowing which moments are your key poses helps you write sharper prompts and plan scenes that actually hold together. If you're storyboarding motion, the same instinct applies — see our guide to how to storyboard for animation and what an animatic is, which is essentially keyframes played back in sequence.

With Scriptly, you skip the frame-by-frame timeline entirely. You chat with an AI director to design characters, plan scenes, and generate video clips — the tool handles the motion between your key story moments so you can focus on the story. If you're new to it, start with making an animated AI short film.

Bringing it together

Keyframes are the vocabulary of motion. Set the moments that matter, let interpolation or in-betweens connect them, and adjust timing by controlling how those connecting frames are spaced. That single concept explains hand-drawn classics, slick motion graphics, and the AI clips being made today.

Ready to turn your key moments into finished scenes? Start creating with Scriptly and direct your first film by chat — no timeline wrangling required.