# Triggers

> The trigger nodes that start a workflow, how each trigger owns its inputs, and how a workflow with several triggers behaves.

A trigger defines how a workflow starts. Every workflow requires at least one trigger, and a new workflow includes a Manual Trigger by default. A workflow without a trigger node cannot be debugged: **Debug** stays unavailable, and the error says that the workflow needs at least one trigger node.

## Trigger types

A new workflow starts with a [Manual trigger](node-manual-trigger.md), which starts a run on demand, for example to test the workflow. To start it another way, replace the Manual trigger from the **Change trigger** list:

![The Change trigger list: Form trigger (Preview), Scheduled trigger, Connector trigger, HTTP Webhook, Incoming call (Preview), Conversation trigger (Preview), and Queue trigger.](https://dev-assets.cms.uipath.com/assets/images/maestro-automate/add-node-change-trigger-automate-0c74f3ee.webp)

- [Form trigger](node-form-trigger.md) (Preview): starts the workflow when a human submits a form.
- [Scheduled trigger](node-scheduled-trigger.md): starts the workflow on a schedule.
- [Connector trigger](node-connector-trigger.md): starts the workflow when an event happens in a connected app.
- [HTTP Webhook](node-http-webhook.md): starts the workflow when a call arrives at a web address.
- [Incoming call](node-incoming-call.md) (Preview): starts the workflow when a phone call arrives.
- [Conversation trigger](node-conversation-trigger.md) (Preview): starts the workflow when a user begins a chat.
- [Queue trigger](node-queue-trigger.md): starts the workflow when a work item is added to a queue.

## Trigger placement

Triggers are added with the **+** button in the bottom toolbar, which opens the **Add node** panel.

After a trigger is added, it appears on the canvas as a circular node. Its output handle connects to the first node of the workflow, which completes the entry point, the place where a run begins.

:::note
Every trigger must connect to at least one node after it. The canvas displays a warning if a trigger has no outgoing connection.
:::

## Trigger inputs

Input variables are owned by their trigger, not by the workflow. Each trigger defines its own set of inputs, and those inputs are only populated when that specific trigger fires.

A node after a trigger references the trigger's input with this syntax:

```javascript
$vars.<triggerName>.output.<inputName>
```

For example, if a Manual Trigger named `manualTrigger1` defines an input called `userId`:

```javascript
$vars.manualTrigger1.output.userId
```

Trigger inputs are called input arguments. They are configured on the **Parameters** tab of the trigger's properties panel, where **Add input argument** adds an argument with a name and a type, such as `string`. The **+** next to the trigger in the **Variables** panel opens the **Add input variable** dialog, which asks for a name, a data type, a description, and a default value. After an argument is defined, it appears under that trigger in the **Variables** panel and is accessible after the trigger as `$vars.<triggerName>.output.<inputName>`.

[Variables and data flow](variables-and-data-flow.md) describes expressions and how data moves between nodes.

## Multiple triggers

A workflow can have more than one trigger. Each trigger acts as a separate entry point. When any trigger fires, it starts an independent run of the workflow.

The same logic can then run in response to different events. For example, a workflow might have both a Scheduled Trigger for nightly batch runs and a connector-based trigger that reacts to incoming requests during the day.

Each trigger owns its own inputs. Nodes after a trigger reference the specific trigger that started the current run. If your workflow has a Manual Trigger named `manualTrigger1` and a Scheduled Trigger named `scheduledTrigger1`, each has its own `$vars.<triggerName>.output` group of values.

The right-click menu of a trigger includes **Set as default entry point**, which sets that trigger as the default entry point of the workflow.

![A canvas with a Manual trigger and a Scheduled trigger, both connected to the same Script node, and the bottom toolbar with the Build as menu set to Maestro Automate.](https://dev-assets.cms.uipath.com/assets/images/maestro-automate/17-two-triggers-automate-669ee6bd.webp)

## Next steps
- [Node reference](node-reference.md): all the categories of the **Add node** panel.
- [Variables and data flow](variables-and-data-flow.md): expressions, node output, and trigger input references.
- [The Flow canvas](flow-canvas.md): the Add node panel, the properties panel, and the bottom toolbar.
- [Error handling](error-handling.md): handling failures in nodes after a trigger.
- [Community](community.md): ask questions and share workflows with other builders on the UiPath Forum.