# Terms used in these guides These names describe what a value does, where it belongs, and who cleans it up. The distinctions matter when connecting data, composing Views, or waiting for an Application to finish starting. ## Models, template data, and state A **model** is one value displayed by a View or represented by a CollectionView's child View. It may be a plain object or a value from your chosen data library. An **ordered model snapshot** is the current sequence returned by `DataApi.models(collection)`. Collection change records refer to those original models through `added`, `removed`, `previous`, and `current`. **Serialized data** is the value prepared for a template. The default `serializeCollection()` returns each model's serialized value; it does not return the raw model snapshot. An override may return another shape. When the View has no model, its template receives that collection serialization result as `models`. See [Rendering](/docs/rendering.md). A **state source** holds state for an Application, MnObject, View, CollectionView, or Behavior. `getState()` returns the source itself, with its own values and methods. State is configured separately from the model or collection a View displays. See [State sources](/docs/state.md). | API | What it connects | | --- | --- | | [`DataApi`](/docs/data-api.md) | Model reads, template serialization, collection order, and data events. | | [`StateApi`](/docs/state.md#stateapi) | State events and cleanup of owned state. | | [`DomApi`](/docs/dom-api.md) | Element creation, selection, content, and attachment. | An **adapter** implements the methods for one or more of these APIs using your chosen tools. Installing an integration package makes its adapter available; configure it on the runtime or class that will use it. DataApi, StateApi, and DomApi support partial overlays: supplied methods replace the corresponding methods, while omitted methods remain inherited. An EventDelegator is a complete replacement. See [Choosing integrations](/docs/choosing-integrations.md) before selecting or implementing an adapter. ## Ownership and cleanup A Behavior's **host View** is the View it is attached to. A **child View** is shown by a Region or managed by a CollectionView. These names describe relationships; a particular child might be a row, a card, or another item in your interface. A **parent Application** owns its registered child Applications. Parents locate and control children; children receive the collaborators they need explicitly. The Application at the top of that hierarchy is its **root Application**. For state, **borrowed** and **owned** describe who is responsible for disposal: - A supplied or declared `state` is borrowed. Destroying an owner releases that owner's subscriptions and leaves the source available to other users. - A `createState()` result is owned. Destroying the owner releases its subscriptions, then calls the selected StateApi's optional `disposeOwned()`. A **cleanup function** releases a subscription or other resource. **Idempotent** means repeated calls have the same effect as one call. Adapters must return idempotent subscription cleanup functions; core does not wrap each returned cleanup to establish that property. ## Default and isolated runtimes The named exports from `marionette` belong to the **default runtime**. `createMarionette()` returns an **isolated runtime** with its own classes, adapter and renderer configuration, and Radio channels. Choose one runtime's classes and setters when composing that part of the application. See [Runtime isolation](/docs/runtime-isolation.md). A state source created for one owner is still an owned state source; it does not create another runtime. Current package imports use `marionette`; historical migration guides may refer to the old `backbone.marionette` package name. ## Application lifecycle and readiness `start()`, `stop()`, `restart()`, and `destroy()` are Application **lifecycle operations**. A **readiness hook** is one of `onBeforeStart`, `onBeforeStop`, or `onBeforeDestroy`. Marionette awaits a Promise returned by one of those hooks before completing that phase. The corresponding `before:*` event listeners are synchronous notifications; their return values are not awaited. `onStart`, `onStop`, `onDestroy`, and their matching events are **completion notifications** and are not awaited either. See [Application lifecycle](/docs/application.md) for ordering, cancellation, and the readiness `AbortSignal`. [Canonical source](/docs/markdown/docs/terminology.md) · [Source identity](/docs/manifest.json)