> ## Documentation Index
> Fetch the complete documentation index at: https://docs.getcollate.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Concepts and Overview

> Understand how notification templates work, the different template types, and the basic structure.

# Concepts and Overview

## How Notification Templates Work

When an event occurs in Collate (e.g., a table is updated, a test case fails), the notification system follows this process:

1. **Triggers** an event subscription configured with a notification template
2. **Renders** the template with live data from the event using Handlebars syntax
3. **Adapts** the rendered HTML for each channel (email as HTML, Slack as formatted blocks, Teams as adaptive cards, etc.)
4. **Sends** the notification to configured destinations

This approach lets you define once and deploy everywhere—a single template automatically formats correctly for email, Slack, Teams, Google Chat, and webhooks.

## Two Template Types

Collate provides two types of notification templates to meet different needs:

### System Templates

Pre-built templates provided by Collate for common notification scenarios.

**Characteristics:**

* Read-only by default (cannot be deleted)
* Can be modified to customize appearance
* Auto-update if you haven't customized them
* Only users with "Edit All" permission can create system templates

System templates are maintained by Collate and improve over time. If you haven't customized a system template, it will automatically update to newer versions when Collate releases improvements.

### User Templates

Custom templates you create for specific business needs:

* Fully editable and deletable
* Custom formatting for domain-specific events
* Reusable across multiple event subscriptions
* Require "Edit All" or "Edit User Notification Template" permission

User templates are completely under your control and won't change unless you explicitly modify them.

## Template Structure

Each template contains two essential parts:

### Template Subject (`templateSubject`)

The email subject line or notification title that appears at the top of messages.

**Constraints:**

* Maximum 256 characters
* Supports Handlebars templating for dynamic content

**Example:**

```
[{{publisherName}}] - {{camelCaseToTitle event.entityType}} Updated: {{entity.fullyQualifiedName}}
```

This renders to something like: `[Data Alerts] - Table Updated: database.schema.customer_data`

<Note>
  Keep the subject line concise (under 100 characters) as it appears in email clients and chat apps where space is limited.
</Note>

### Template Body (`templateBody`)

HTML content with Handlebars placeholders that forms the main notification message.

**Constraints:**

* Maximum 10,240 characters
* Supports HTML formatting and Handlebars templating
* Automatically adapted by Collate for each channel

**Example:**

```html theme={null}
<strong>{{event.userName}}</strong> changed <strong>{{camelCaseToTitle event.entityType}}</strong>:
<a href="{{buildEntityUrl event.entityType entity}}">{{entity.fullyQualifiedName}}</a>

{{#if changes.updates}}
<h3>Updated Fields:</h3>
<ul>
  {{#each changes.updates}}
  <li><strong>{{name}}</strong>: {{oldValue}} → {{newValue}}</li>
  {{/each}}
</ul>
{{/if}}
```

Collate intelligently transforms this HTML for each channel:

* **Email**: Renders as formatted HTML with links
* **Slack**: Converts to Slack block format with proper formatting
* **Teams**: Converts to Adaptive Cards format
* **Google Chat**: Converts to Google Chat message format
* **Webhooks**: Sends the raw template data

<Warning>
  Template bodies are limited to 10,240 characters. If your template exceeds this, consider splitting it into multiple templates for different use cases or simplifying the logic.
</Warning>

## Next Steps

* **New to templates?** → Start with [Create and Manage Templates](/how-to-guides/data-quality-observability/alerts-notifications/notification-templates/create-and-manage-templates)
* **Want to write templates?** → Learn [Handlebars Templating Guide](/how-to-guides/data-quality-observability/alerts-notifications/notification-templates/handlebars-templating-guide)