# Glossary > Watasu vocabulary in plain language. ## Add-on A managed service attached to an app — PostgreSQL, Valkey, ClickHouse, Redpanda, object storage, or one of the observability services (logs, metrics, traces). See [Add-ons Overview](https://docs.watasu.io/addons/overview.md). ## Alias A prefix applied to an add-on's exported env vars when the same kind of service is attached to an app more than once. `watasu addons:attach reporting-db --as REPORTING` makes `DATABASE_URL` from that add-on show up as `REPORTING_DATABASE_URL`. ## App The deployable unit on Watasu. Owns its source, builds, releases, configuration, processes, attached add-ons, and domains. See [Core Concepts → App](https://docs.watasu.io/getting-started/concepts.md#app). ## App trust The mechanism that lets one app reach another app's private TCP services. See [Private Networking](https://docs.watasu.io/apps/private-networking.md). ## Build The process of turning source code into a container image. Watasu uses your `Dockerfile` if present, otherwise Cloud Native Buildpacks. See [Deploy an App](https://docs.watasu.io/apps/deploy.md#how-watasu-builds-your-code). ## Buildpack A standardized way to build container images from source without writing a `Dockerfile`. Watasu uses Cloud Native Buildpacks. ## Config var An environment variable Watasu injects into your app's processes. Set with `watasu config:set`, listed with `watasu config`. Each var is either **plain** (any maintainer can read and edit) or **secret** (only the app owner can read or edit; maintainers see the key with a redacted value). Either way, the real value is injected into your processes at runtime. See [Configuration](https://docs.watasu.io/apps/configuration.md). ## Domain A public hostname pointing at a public web process. Watasu manages TLS automatically. See [Custom Domains](https://docs.watasu.io/apps/custom-domains.md). ## Follower A streaming read replica of a PostgreSQL database. Useful for offloading reporting queries. See [PostgreSQL → Followers](https://docs.watasu.io/addons/postgresql.md#followers-read-replicas). ## Formation The set of process types, replica counts, and pod sizes for an app. Inspect with `watasu pods`, change with `watasu pods:scale` and `watasu pods:type`. See [Processes and Scaling](https://docs.watasu.io/apps/processes-and-scaling.md). ## Grafana The observability UI for an app — dashboards, log search, metrics queries, trace inspection, alerts. Created automatically the first time you attach a logs, metrics, or traces add-on. See [Observability Overview](https://docs.watasu.io/observability/overview.md). ## MCP The Model Context Protocol — how AI assistants connect to Watasu for read-only visibility into apps, builds, and add-ons. Hosted at `mcp.watasu.io`. See [Connect AI Assistants](https://docs.watasu.io/workflows/mcp.md). ## Pipeline A grouping of apps representing stages of the same product (`staging`, `production`) with promotion between them. See [Pipelines and Promotions](https://docs.watasu.io/workflows/pipelines.md). ## Plan A tier of an add-on, identified by a slug like `postgresql:standard-0`. Plans differ on size, durability, replication, and backup behavior. See [Add-on Plans](https://docs.watasu.io/reference/addon-plans.md). ## Pod One running instance of a process. The app's formation determines how many pods exist for each process type and how big each one is. ## Pod size The CPU and memory shape assigned to each pod. Ranges from `hobby` to `standard-16x`. See [Pod Sizes](https://docs.watasu.io/reference/pod-sizes.md). ## Procfile A file at the root of your repo that declares process types and the command for each. See [Deploy an App → Process types and the Procfile](https://docs.watasu.io/apps/deploy.md#process-types-and-the-procfile). ## Process A named workload inside an app. The name suffix decides routing: `web`/`*-web` is publicly routed HTTP, `*-tcp` is private TCP for microservices, `*-rtc` is public UDP with a dedicated TURN gateway for WebRTC, `release` runs once per deploy, anything else is unrouted (typically workers). See [Processes and Scaling](https://docs.watasu.io/apps/processes-and-scaling.md) for the full table. ## RTC process A process whose name ends in `-rtc`. Watasu provisions a dedicated TURN gateway, a public UDP port, and per-replica public hostnames, then injects `TURN_*` env vars into the container. Used for WebRTC SFUs, voice agents, and real-time apps. See [Real-Time and WebRTC](https://docs.watasu.io/apps/realtime.md). ## Release process A process named `release` (or `-release` for prefix-scoped gating). Runs once per deploy, before the new release goes live. Use for migrations and one-time per-release setup. A failing release process aborts the deploy. See [Processes and Scaling → The release process](https://docs.watasu.io/apps/processes-and-scaling.md#the-release-process). ## TCP process A process whose name ends in `-tcp`. Reachable as a private TCP endpoint by other apps that explicitly trust this app. Used for internal microservice traffic. See [Private Networking](https://docs.watasu.io/apps/private-networking.md). ## Promotion Copying a release's image into the next pipeline stage. The image stays the same; the new stage runs it with its own config and add-ons. See [Pipelines and Promotions](https://docs.watasu.io/workflows/pipelines.md). ## Release An immutable snapshot of "what's live" — image, formation, config vars, attached add-ons. Every deploy and every config change creates a new release. See [Logs and Releases](https://docs.watasu.io/apps/logs-and-releases.md). ## Review app A temporary, fully working environment created automatically for a pull request. Requires `app.json`. See [Review Apps](https://docs.watasu.io/workflows/review-apps.md). ## Sandbox An isolated Linux workspace created from a sandbox template version. Use sandboxes for agent tasks, code execution, file operations, preview ports, and checkpoints. See [Sandboxes Overview](https://docs.watasu.io/sandboxes/overview.md). ## Sandbox resources The CPU, memory, network, TTL, and price settings for a sandbox. Root disk size is platform-managed. See [Sandboxes Billing](https://docs.watasu.io/sandboxes/billing.md). ## Sandbox template A reusable environment definition for sandboxes. Template versions are built artifacts that new sandboxes start from. See [Sandbox Templates](https://docs.watasu.io/sandboxes/templates.md). ## Team The ownership boundary for apps, add-ons, and sandboxes. Members get access at the level you grant them. See [Teams and Access](https://docs.watasu.io/admin/teams-and-access.md). [View this page on the web](https://docs.watasu.io/reference/glossary/)