# 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 `DefaultDomain` has the following yaml definition:

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

actions:
- utter_greet
- utter_cheer_up
- utter_did_that_help
- utter_happy
- utter_goodbye
- utter_iamabot

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.

[Slots](https://legacy-docs-v1.rasa.com/1.7.0/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/1.7.0/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?"
   ```

Afterward, you can use the response as an action in the stories:

```yaml
   ## greet the user
   * intent_greet
     - utter_greet
   ```

When `utter_greet` is run as an action, it will send the message from the response back to the user.

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. Note that since the domain is in yaml format, the json payload should first be converted to yaml format.

```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**

```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. You can either do that in your custom python code or by using the automatic slot filling mechanism. For example, if you have a response like this:

```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, e.g.:

```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.

```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
```

Note that the `session_start` action will still be triggered at the very beginning of conversations.