‹ Overview
Glossary
The words used across the bitHuman docs and what each one means.
What each term means here, and the page that owns it. The short version, for a first read, is Key terms.
Models and avatars
| Term | Meaning |
|---|---|
Essence 2 (essence-2) | The model that renders a photoreal person from one portrait. Essence 2 |
Expression 2 (expression-2) | The model that renders any character from one portrait. Expression 2 |
Essence 1, Expression 1 (essence-1, expression-1) | The first generation of the models. First generation |
| Avatar | The face that talks: one character, made from one portrait. It turns speech audio into lip-synced video. |
| Agent | An avatar together with its persona, voice and knowledge, created in the bitHuman app or with the Agents API. |
| Agent code | The identifier of an agent, for example A23WJF0199. Request fields name it agent_id or agent_code, and examples read it from BITHUMAN_ or BITHUMAN_: all take the same code. Agent codes |
| Sample avatars | Public agents anyone can use without an account: wise-pup (agent code A23WJF0199, Expression 2) and sofia-ramirez (A52DHS2219, Essence 2). The CLI takes either the name or the code. Showcase list |
Avatar file (.imx) | One agent’s model files in one container, downloaded once and rendered on your hardware. The Essence 2 SDKs call it an identity. The avatar file |
| Persona | The agent’s system prompt: who it is and how it answers. Persona |
| Gestures | A named motion (wave, nod, clap) an avatar plays when your code asks; the API calls them dynamics. Gestures |
| Idle | The motion an avatar shows between replies, so it never freezes. |
Where it runs
| Term | Meaning |
|---|---|
| Renders / runs | The avatar renders (on the device, in the browser, on your server or in the bitHuman cloud); the conversation runs (in your stack, in the CLI’s local conversation brain, or on bitHuman’s servers). |
| On the device | The avatar renders on the user’s iPhone, iPad, Mac or Android phone. On the device |
| CPU only (no GPU) | The avatar renders on a standard Linux PC with no graphics card. CPU only |
| Self-hosted (your servers) | The avatar renders on a computer or server you run: the CLI, the Python SDK, the LiveKit plugin or Pipecat. It bills the lower self-hosted rate. Your servers |
| bitHuman cloud | The avatar renders on bitHuman’s servers and streams to any screen, at the cloud rate. bitHuman cloud |
| LiveKit room | A real-time audio and video session on a LiveKit server. A voice agent and the avatar join it as participants, and so do your users. LiveKit |
| Fully offline | A license for real-time avatars with no internet connection. Fully offline |
| File rendering | Turning an audio file into a talking-avatar video with bithuman render or the Python SDK. It signs in online; it is not the offline license. Talking video |
| WebGPU | The browser graphics interface the web embed uses to render the avatar in the tab (render=local). Web |
| Local conversation brain | The CLI mode (BITHUMAN_) that runs speech recognition, the language model and the voice on a Mac or Linux PC. Local conversation brain |
| × real time | Seconds of avatar video rendered per second. At 1.0× or more an avatar holds a live conversation. Performance |
Credentials and billing
| Term | Meaning |
|---|---|
| API secret | The one credential for every surface, read from BITHUMAN_; REST sends it in the api-secret header. Your API secret |
| Embed token | A short-lived token your server mints so a web page can open a private agent without the secret. Embedding |
| Runtime token | A short-lived token for a LiveKit room or a download, minted with the API secret. Authentication |
| Credits | What usage is paid in: 100 credits = $1. Pricing and credits |
| Session | One avatar running, from start to stop. It bills while it runs, talking or idle. Pricing |
| Managed agent, chat line | bitHuman runs the whole conversation (listening, the replies, the voice) and the avatar, for one all-inclusive rate of 10 credits a minute. Pricing |
| Active session time | What real-time usage bills: the time a session is open, talking or idle, to the second. Pricing |
| Creator plan | The plan API and SDK use requires, or a higher one. Plans |
Next
This section moved: docs.bithuman.ai/resources/renamed#older-names