# Core concepts

> https://docs.errora.org/en/getting-started/concepts

## Organization

The billing and membership boundary. Every user gets a **personal organization** on signup
and can create more. An organization owns:

- **projects**
- **members** and their roles
- a **wallet** (Toman) and its pay-as-you-go usage
- **integrations**, **AI configurations**, **notification channels** and **alert rules**
- **dashboards**
- a **retention policy** (`retention_days`)

## Project

One application or service. A project owns its events, issues, logs, replays, monitors,
metrics, profiles and feedback. Projects have a **platform** (for the icon and setup
snippet) and a **sample rate** — the fraction of arriving events that get stored
(`1.0` keeps everything).

## DSN key

The credential an SDK uses to send data:

```text
https://<public_key>@<host>/<project_id>
```

A project can have several keys (`label`, `public_key`, `is_active`) so you can rotate one
without downtime. The public key is what authenticates ingestion — via the `X-Sentry-Auth`
header, a `?sentry_key=` query parameter, or the `dsn` field of an envelope header.

## Event

One thing that happened: an exception, a message, a transaction, a log record, a replay
segment, a check-in, a metric bucket or a feedback submission. SDKs post events as
**envelopes** to `/api/<project_id>/envelope/` (or the legacy `/store/` endpoint for plain
error events).

## Issue (group)

Events are **fingerprinted** — by exception type plus stack trace, Sentry-style — and
identical fingerprints collapse into one **issue**. The issue tracks:

- `times_seen`, unique users, first seen / last seen
- status: `unresolved`, `resolved`, `ignored`, `archived`
- assignment and bookmarks
- 24h / 30d trend series

If a new event arrives for an issue you already resolved, the issue **regresses** back to
unresolved and fires the `issue.regressed` alert event.

## Trace and span

A **trace** ties together everything that happened during one logical operation, across
services. A **transaction** is the root span of one service's work; **spans** are the
nested units of work inside it (an HTTP call, a SQL query, an LLM call). Logs, profiles,
replays and check-ins carry the `trace_id` too, which is how the UI can jump from a log
line to the transaction that produced it.

## Environment and release

- **Environment** (`production`, `staging`, …) separates the same code running in different
  places. Cron monitors keep per-environment state; issues, logs and feedback can be
  filtered by it.
- **Release** (`myapp@1.4.2`) tags every event with the version that produced it, and is the
  key that [source maps](/en/products/source-maps) are uploaded under.

Set both in the SDK:

```python
sentry_sdk.init(dsn="…", environment="production", release="myapp@1.4.2")
```

## Sampling

Two independent knobs:

- **SDK-side** — `traces_sample_rate`, `profiles_sample_rate`,
  `replaysSessionSampleRate` decide what the client sends.
- **Server-side** — the project's `sample_rate` decides what Errora stores from what arrives.

Both reduce cost. SDK-side sampling also reduces the load on your own app.

## Retention

Each organization sets `retention_days`. A nightly job deletes events, logs and replays past
that age (and issues left empty), falling back to `DATA_RETENTION_DAYS_DEFAULT` (90 days).
See [Data retention](/en/account/retention).

## Roles and capabilities

Roles are `owner`, `admin`, `member`, `billing`, `viewer`, applied **per organization** and
optionally **per project**, resolved through a capability matrix (`org:manage`,
`project:manage`, `issue:write`, `ai:trigger`, …). See
[Roles & permissions](/en/account/organizations#roles--permissions).