---
title: "Glossary"
description: "Quick definitions for every term used across the Pug docs, SDKs and API."
---

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

# Glossary

Quick reference for terms used across the Pug docs, SDKs, and API. Definitions are kept concise — follow the linked pages for full explanations.

| Term | Definition |
|------|------------|
| **Organization** | Top-level tenant. Owns members, billing, and email configuration. Projects belong to an organization. See [Core concepts](/get-started/concepts). |
| **Project** | Isolated data boundary inside an organization. Owns events, profiles, insights, and API keys. All analytics queries are project-scoped. See [Core concepts](/get-started/concepts). |
| **Public key** (`pub_…`) | Project-scoped write credential for client SDKs. Sent as `x-api-key`; lets you ingest events and identify users, but cannot read analytics. Safe to ship in a browser bundle or mobile binary. See [Authentication](/get-started/authentication). |
| **Private key** (`prv_…`) | Project-scoped read/write credential for trusted server-side code. Sent as `x-api-key`; reaches `shared.*` services (insights, profiles). Never ship in client code. See [Authentication](/get-started/authentication). |
| **Event** | A named occurrence with custom properties and a timestamp — the atomic unit of analytics data. The event name is its `kind`; names starting with `pug.` are reserved. See [Events API](/api/events). |
| **Property** | A custom key/value pair attached to an event (string, integer, double, boolean, or timestamp). Keys must not start with `$`. Sent in `customProperties` on each event. |
| **Auto-property** | A `$`-prefixed property attached automatically by the SDK or server — for example `$url`, `$browser`, `$country`. `$`-prefixed keys are reserved and cannot be set as custom properties. See [Auto-properties](/reference/auto-properties). |
| **Well-known event** | A standard event name (e.g. `page_view`, `purchase`) that carries a typed schema. Custom event names not in the registry are also accepted without schema validation. See [Well-known events](/reference/well-known-events). |
| **Profile** | A persistent record representing one user — identified or anonymous — with an accumulated set of traits (properties). Created or updated by `identify()`. See [Profiles API](/api/profiles). |
| **Anonymous ID** | An SDK-generated identifier in the form `anon-…`, created when a visitor first arrives. Events are attributed to this ID until the user is identified. |
| **External ID** | Your stable user identifier (e.g. a database user ID), passed as `external_id` to `Identify`. Use a value that does not change — not an email address. |
| **Distinct ID** | The identifier an event is attributed to: the anonymous ID before `identify()` is called, the external ID after. Stored as `distinct_id` on every event. |
| **Alias** | The association of multiple identifiers with one profile — most commonly the anonymous-to-identified merge on the first `identify()` call (there is no separate `alias()` method). See [Profiles API](/api/profiles). |
| **Session** | A window of activity grouped by the SDK. A new session starts after the idle timeout (default 30 min) or the maximum session duration (default 24 h). The session ID is synced across browser tabs. See [Core concepts](/get-started/concepts). |
| **Insight** | A server-side analytics query specification — event selection, filters, time range, granularity, aggregation, and optional breakdowns. The same spec powers dashboard charts and the `InsightsService` API. Types: `TRENDS`, `SEGMENTATION`, `FUNNEL`, `RETENTION`, `USER_FLOW`, `TOP_K`. See [Insights API](/api/insights). |
| **Connect RPC** | The API transport protocol used by all Pug services. Supports the Connect, gRPC, and gRPC-Web protocols over HTTP/1.1 and HTTP/2. Request path format: `/<package>.<Service>/<Method>`. See [Authentication](/get-started/authentication) and the [API overview](/api). |
| **Batch** | A single `BatchCreate` call carrying up to 1 000 events. All event ingestion goes through this endpoint — there is no single-event API. See [Events API](/api/events). |
| **Tracking consent** | The Web SDK's three-state capture gate — `granted`, `cookieless` (events flow, nothing stored on the device), or `denied`. Defaults to `cookieless`. See [Tracking consent](/sdks#tracking-consent). |

## Further reading

- [Core concepts](/get-started/concepts) — detailed explanations of key terms
- [Authentication](/get-started/authentication) — keys, headers, and error codes
- [Profiles API](/api/profiles) — identity lifecycle, anonymous → identified merge
- [Insights API](/api/insights) — query types and spec format
- [Auto-properties](/reference/auto-properties) — full `$`-prefixed property catalog

Source: https://docs.pug.sh/reference/glossary/index.mdx