# Domains

The `Domain` defines the universe in which your assistant operates. It specifies the `intents`, `entities`, `slots`, and `actions` your bot should know about. Optionally, it can also include `responses` for the things your bot can say.

## An example of a Domain

As an example, the domain created by `rasa init` has the following yaml definition:

```yaml
intents:
  - greet
  - goodbye
  - affirm
  - deny
  - mood_great
  - mood_unhappy
  - bot_challenge

responses:
  utter_greet:
  - text: "Hey! How are you?"

utter_cheer_up:
  - text: "Here is something to cheer you up:"
    image: "https://i.imgur.com/nGF1K8f.jpg"

utter_did_that_help:
  - text: "Did that help you?"

utter_happy:
  - text: "Great, carry on!"

utter_goodbye:
  - text: "Bye"

utter_iamabot:
  - text: "I am a bot, powered by Rasa."

session_config:
  session_expiration_time: 60
  carry_over_slots_to_new_session: true
```

**What does this mean?**

Your NLU model will define the `intents` and `entities` that you need to include in the domain. The `entities` section lists all entities extracted by any [entity extractor](https://legacy-docs-v1.rasa.com/1.9.5/nlu/entity-extraction/#entity-extraction) in your NLU pipeline.

For example:

```yaml
entities:
   - PERSON          # entity extracted by SpacyEntityExtractor
   - time            # entity extracted by DucklingHTTPExtractor
   - membership_type # custom entity extracted by CRFEntityExtractor
   - priority        # custom entity extracted by CRFEntityExtractor
```

[Slots](https://legacy-docs-v1.rasa.com/1.9.5/core/slots/#slots) hold information you want to keep track of during a conversation. A categorical slot called `risk_level` would be defined like this:

```yaml
slots:
   risk_level:
      type: categorical
      values:
      - low
      - medium
      - high
```

[Actions](https://legacy-docs-v1.rasa.com/1.9.5/core/actions/#actions) are the things your bot can actually do. For example, an action could:

- respond to a user,
- make an external API call,
- query a database, or
- just about anything!

## Custom Actions and Slots

To reference slots in your domain, you need to reference them by their **module path**. To reference custom actions, use their **name**. For example, if you have a module called `my_actions` containing a class `MyAwesomeAction`, and module `my_slots` containing `MyAwesomeSlot`, you would add these lines to the domain file:

```yaml
actions:
  - my_custom_action
  ...

slots:
  - my_slots.MyAwesomeSlot
```

## Responses

Responses are messages the bot will send back to the user. There are two ways to use these responses:

1. If the name of the response starts with `utter_`, the response can directly be used as an action. You would add the response to the domain:

```yaml
responses:
     utter_greet:
  - text: "Hey! How are you?"
```

2. You can use the responses to generate response messages from your custom actions using the dispatcher: `dispatcher.utter_message(template="utter_greet")`.

## Images and Buttons

Responses defined in a domain’s yaml file can contain images and buttons as well:

```yaml
responses:
  utter_greet:
  - text: "Hey! How are you?"
    buttons:
    - title: "great"
      payload: "great"
    - title: "super sad"
      payload: "super sad"
  utter_cheer_up:
  - text: "Here is something to cheer you up:"
    image: "https://i.imgur.com/nGF1K8f.jpg"
```

## Custom Output Payloads

You can also send any arbitrary output to the output channel using the `custom:` key. For example:

```yaml
responses:
  utter_take_bet:
  - custom:
      blocks:
      - type: section
        text:
          text: "Make a bet on when the world will end:"
          type: mrkdwn
        accessory:
          type: datepicker
          initial_date: '2019-05-21'
          placeholder:
            type: plain_text
            text: Select a date
```

## Channel-Specific Responses

For each response, you can have multiple **response templates**. If you have certain response templates that you would like sent only to specific channels, you can specify this with the `channel:` key.

```yaml
responses:
  utter_ask_game:
  - text: "Which game would you like to play?"
    channel: "slack"
    custom:
      - # payload for Slack dropdown menu to choose a game
  - text: "Which game would you like to play?"
    buttons:
    - title: "Chess"
      payload: '/inform{"game": "chess"}'
    - title: "Checkers"
      payload: '/inform{"game": "checkers"}'
    - title: "Fortnite"
      payload: '/inform{"game": "fortnite"}'
```

## Variables

You can also use **variables** in your responses to insert information collected during the dialogue. For example:

```yaml
responses:
  utter_greet:
  - text: "Hey, {name}. How are you?"
```

## Variations

If you want to randomly vary the response sent to the user, you can list multiple **response templates** and Rasa will randomly pick one of them:

```yaml
responses:
  utter_greeting:
  - text: "Hey, {name}. How are you?"
  - text: "Hey, {name}. How is your day going?"
```

## Ignoring entities for certain intents

If you want all entities to be ignored for certain intents, you can add the `use_entities: []` parameter to the intent in your domain file like this:

```yaml
intents:
  - greet:
      use_entities: []
```

## Session configuration

A conversation session represents the dialogue between the assistant and the user. You can define the period of inactivity after which a new conversation session is triggered in the domain under the `session_config` key. The default session configuration looks as follows:

```yaml
session_config:
  session_expiration_time: 60  # value in minutes, 0 means infinitely long
  carry_over_slots_to_new_session: true  # set to false to forget slots between sessions
```

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