# Overview (Dialogflow)

In order for users to engage with your Action, they need to invoke it. In many
cases users will have your specific Action in mind, so they ask the Google
Assistant to interface with it. Additionally, as long as you design your Action
to accomplish specific, helpful tasks, the Assistant may recommend it to users
when it's the best available Action for their query.

The following sections explain the different types of invocation and
describe how best to design your Action with discovery in mind.

## Invocation types

There are two types of Action invocation:

- **Explicit Invocation** occurs when users tell the Assistant that they
  explicitly want to use your Action. You have the most control over how your
  users explicitly invoke your Action, but you need to let your users know
  what phrases start a conversation with your Action. The **Ask Your
  Assistant** section on your Action's [directory listing](https://developers.google.com/assistant/directory) is a
  good place to relay this information to users.

  Example: "*Hey Google, talk to Wayne's Bikes.*"
- **Implicit Invocation** occurs when the Assistant chooses to invoke your
  Action without users calling it by name. The most common example of an
  implicit invocation is when users tell the Assistant they want to accomplish
  a certain task (by stating an [invocation phrase](https://developers.google.com/assistant/df-asdk/discovery#invocation_phrases)), and
  the Assistant opts to invoke your Action for that task because it can
  fulfill the user's intent. Implicit invocation enables users to learn about
  and use your Action simply by going about their day, but designing your
  Action with our [best practices](https://developers.google.com/assistant/df-asdk/checklist) in mind improves the
  chances that it's discovered.

  Example: "*Hey Google, book an appointment to fix my bike.*"

> [!NOTE]
> **Note:** You don't have to choose between types of invocation for your Action. Users can always explicitly invoke your Action, but you should keep implicit invocation in mind during the design process so you can increase the odds that users discover your Action on their own.

## Invocation Phrases

An invocation phrase describes a specific function of your Action. When users
invoke your Action, they may include an invocation phrase that can deep link
into one of your Action's specific functions.

Examples of invocation phrases include:

- "*what should I wear today*"
- "*when's the next bus to $location*"
- "*what's the current price of gold*"
- "*want to meditate*"

Users can append an invocation phrase to the end of an explicit invocation or
them on their own for an implicit invocation. Either way, make sure to design
useful invocation phrases that are specific to your Action's purpose. Invocation
phrases that are too generic aren't helpful to the user and reduce your Action's
visibility and discovery.

For more information about invocation, discovery, and invocation phrases,
read [explicit](https://developers.google.com/assistant/df-asdk/discovery/explicit) and [implicit](https://developers.google.com/assistant/df-asdk/discovery/implicit) invocation.

## Assistant links

In addition to invocation using the Assistant, you can also enable an
[Assistant link](https://developers.google.com/assistant/engagement/assistant-links) for any of your Actions. Users who click on this link in a web
or mobile browser are directed to the Google Assistant, where they'll start
a conversation with that specific Action.