Animation terms, in plain English.
The words you'll meet when shipping character animation in apps and on the web.
- .riv file
- Rive's compact binary export format. One .riv can hold artboards, animations and state machines, and is played by a Rive runtime library; you do not need the Rive editor to play or control it in an app. Guide
- Alpha channel
- An extra channel in an image or video that stores how opaque each pixel is, from fully transparent to fully solid. Partial alpha is what lets soft edges and shadows blend smoothly over any background. Guide
- AnimatedVectorDrawable
- Android's built-in format for animating vector graphics. The Android 12+ splash screen accepts one as its icon, and Google recommends keeping that animation to 1,000 ms or less on phones. Guide
- Autoplay policy
- Browser rules that decide when media may start without a user action. Muted autoplay is generally allowed; video with sound usually needs prior user interaction, and
play()returns a Promise that rejects when blocked. Guide - Blend (transition)
- A transition that mixes two animations over a set duration instead of cutting between them, so a character eases from one state into the next. Blend states can also mix several animations based on a numeric value. Guide
- Bodymovin
- The Adobe After Effects plugin that exports compositions as Lottie JSON. It is the traditional bridge from an After Effects timeline to a Lottie player in an app or website. Guide
- Bone rig
- A hierarchy of bones attached to artwork so that rotating or moving one bone deforms the connected parts. Rigs make it practical to pose and animate characters and logos without drawing every frame. Guide
- Data binding (view model)
- Rive's newer way to connect app data to an animation. A view model defines typed properties, including numbers, strings, enums, colors, lists, images and triggers, that the file binds to, replacing state machine inputs for new projects. Guide
- dotLottie (.lottie)
- A compressed, MIT-licensed container format maintained by LottieFiles. One .lottie file can package several Lottie animations, shared assets, themes and interactive state machines. Guide
- GIF
- A decades-old image format that supports simple animation. Each frame is limited to a 256-color palette and only one fully transparent color, so GIFs band, have jagged edges and are usually much larger than equivalent video. Guide
- HEVC (H.265)
- A video codec that compresses better than H.264. Apple added HEVC with alpha in iOS 13 and macOS Catalina, which Safari uses to play transparent video, usually stored in a .mov tagged
hvc1. Guide - Idle animation
- The calm, low-movement loop a character plays when nothing else is happening, such as breathing or blinking. It keeps the character alive on screen without pulling attention from the content. Guide
- Launch screen
- The static screen iOS shows while an app starts. It is defined in Info.plist or a storyboard without custom code, so it cannot animate; Apple recommends it look nearly identical to the app's first screen. Guide
- Loop vs one-shot
- A loop repeats for as long as its state is active, such as idle or loading. A one-shot plays once in response to an event, such as success or error, and then hands back to the current loop. Guide
- Lottie
- An open animation format and set of players for web, iOS, Android, React Native and Windows that render After Effects animations exported as JSON. With dotLottie state machines, added to Lottie Creator in 2025, Lottie files can also be interactive. Guide
- Mascot
- A character that represents a brand or product. In apps, an animated mascot often carries product states such as loading, empty screens, success and errors, giving feedback a consistent personality. Guide
- Mesh deformation
- Bending an image by attaching it to a grid of points and moving those points, instead of redrawing it. It lets raster artwork, such as a PNG logo, bend and flex while keeping its original pixels. Guide
- MOV
- Apple's QuickTime container format. On the web it is mainly used to deliver HEVC-with-alpha video to Safari; in editing tools it often holds ProRes masters. Guide
- playsinline
- A
<video>attribute that lets iPhone Safari play a video inside the page instead of switching to fullscreen. Together withautoplayandmuted, it is required for GIF-like inline loops on iOS. Guide - prefers-reduced-motion
- A CSS media feature with the values
no-preferenceandreducethat reflects the user's OS Reduce Motion setting. Sites use it to replace large movement and loops with a static pose or a fade. Guide - ProRes 4444
- An Apple editing codec that stores high-quality color plus an alpha channel. It is a good master for transparent animation, but its files are far too large to serve on a website, so you encode WebM and HEVC from it. Guide
- Rive
- An interactive animation tool made of a design editor and open-source, MIT-licensed runtimes for web, React, Apple platforms, Android, Flutter and React Native. Animations are exported as .riv files that can react to app state through a state machine. Guide
- SplashScreen API
- Android's system splash screen, introduced in Android 12 and backported by
androidx.core:core-splashscreen. It shows your app icon, which may be animated, on a background color while the app starts. Guide - Squash and stretch
- A classic animation principle where a shape compresses on impact and elongates in fast motion while keeping its volume. It makes even a rigid logo feel springy and alive. Guide
- State machine
- Logic stored inside an animation file that connects states, such as idle, loading and success, with transitions. App code changes values and the state machine decides which animation plays and how it blends into the next. Guide
- State machine input
- A named value your code sets to drive a Rive state machine. Inputs come in three types: number, boolean and trigger. Rive now calls inputs a legacy system and recommends data binding for new work, though existing files keep working. Guide
- Trigger
- A state machine input with no stored value. Firing it causes a one-time transition, which makes it the natural fit for momentary reactions such as success, error or a wave. Guide
- VP9
- An open video codec from Google, usually stored in a WebM file. VP9 can carry an alpha channel, which Chrome, Edge and Firefox render as transparency; Safari plays VP9 but ignores the alpha. Guide
- WCAG 2.2.2 Pause, Stop, Hide
- A Level A accessibility criterion: moving or blinking content that starts automatically, lasts more than five seconds and appears alongside other content needs a way to pause, stop or hide it, unless it is essential. Guide
- WebM
- An open media container for the web, typically holding VP8, VP9 or AV1 video. A VP9 WebM with alpha is the standard way to serve transparent video to Chromium browsers and Firefox. Guide