> ## Documentation Index
> Fetch the complete documentation index at: https://docs.elata.bio/llms.txt
> Use this file to discover all available pages before exploring further.

# Glossary

> Plain-language definitions of the terms used across the Elata docs.

**Alpha waves.** A rhythm in EEG between about 8 and 12 Hz, often stronger when
a person is relaxed with their eyes closed.

**App state.** Small pieces of data, such as saves and settings, that an app
stores for a user through Elata. Scoped to that app and that user.

**Artifact.** In EEG, a signal that doesn't come from the brain, such as a
blink, jaw clench, or loose sensor. Artifacts are usually much larger than
brain activity.

**Band power.** How much of an EEG signal falls in a frequency band, such as
alpha or beta. The basis of most "calm" and "focus" measures.

**Biometric Score.** An optional, cross-app measure (0 to 100) built from
derived session results, only with the user's consent. See
[Privacy and consent](/overview/privacy-and-consent).

**Biosignal.** A measurable signal from the body, such as a heartbeat or the
brain's electrical activity.

**Consent.** A user's explicit, revocable permission for an app to contribute
derived results to their Score. Requested by Elata, not by the app.

**Derived result.** A summary computed from raw signals, such as average heart
rate over a session. Raw signals are never part of it.

**EEG (electroencephalography).** Measuring the brain's electrical activity
through sensors on the scalp.

**Elata.** The marketplace at [app.elata.bio](https://app.elata.bio) where
biosignal apps are published and played.

**Elata Points.** Off-chain, non-transferable points earned for taking part on
Elata. See [Points](/overview/points).

**Elata SDK.** Open-source packages for building biosignal apps. See
[The Elata SDK](/overview/elata-sdk).

**ELTA.** The ERC-20 token for the Elata ecosystem, on Base. See
[ELTA token](/overview/elta-token).

**Federated learning.** Training a model across many devices without
collecting their raw data in one place. Planned research direction for Elata.

**Host bridge.** The set of messages an app uses to ask Elata for things like
purchases and saved progress. See [Host bridge](/apps/platform/host-bridge).

**HRV (heart-rate variability).** The variation in time between heartbeats.
Often linked to recovery and stress, and sensitive to recording conditions.

**[Muse](choosemuse.com).** A consumer EEG headband line (Muse 2, Muse S, and the newer Muse S Athena) supported by the Elata SDK.

**PPG (photoplethysmography).** Measuring pulse by shining light into the skin
and detecting changes in the reflected light, as smartwatches do.

**Release.** One version of an app on Elata. Every release is scanned and
reviewed before it goes public.

**rPPG (remote photoplethysmography).** Estimating pulse from a camera by
detecting tiny color changes in the skin.

**Sandbox.** The isolated environment each app runs in, on its own web origin,
so it can't see who the user is or access their account.

**Web Bluetooth.** A browser feature that lets web pages connect to Bluetooth
devices. Available in Chrome and Edge, not in Safari or iOS browsers.

**WebAssembly (WASM).** A format that lets fast, compiled code run in the
browser. The Elata SDK's signal processing runs as WebAssembly.


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