# Creating subdomains

Copy as Markdown[View as Markdown](/docs/development/guides/domains/creating-domains/subdomains.md)

***

**Added in** `eventcatalog@2.34.0`

Subdomains are optional in EventCatalog but can be a great way to group domains together.

Some organizations have multiple domains, and each domain may have multiple subdomains.

When you add a subdomain to a domain, your users will be able to see the relationship between the domain and subdomain, and be able to navigate between them.

### What do subdomains look like in EventCatalog?[​](#what-do-subdomains-look-like-in-eventcatalog "Direct link to What do subdomains look like in EventCatalog?")

![Example](/assets/images/subdomain-example-5a047c9099516a034d7e2878349de49d.png)

*See [subdomain example](https://demo.eventcatalog.dev/docs/domains/E-Commerce/1.0.0) in the EventCatalog Demo.*

#### Domains Visualizer (with subdomains)[​](#domains-visualizer-with-subdomains "Direct link to Domains Visualizer (with subdomains)")

When you reference a subdomain from a domain, it will appear in the domains visualizer. You can use the legend to highlight resources that are part of a subdomain.

![Domains Visualizer (with subdomains)](/assets/images/subdomain-visualizer-8de136c9ffdd97334f813d6b8850eaa5.png)

*See [subdomain example](https://demo.eventcatalog.dev/visualiser/domains/E-Commerce/1.0.0) in the EventCatalog Demo.*

## Adding subdomains[​](#adding-subdomains "Direct link to Adding subdomains")

A subdomain is just another domain resource. But a parent domain references the subdomains.

First you need to create your subdomain.

You can create a subdomain in the `/domains` folder or in a `/subdomains` folder.

**Examples**

1. `/domains/MySubDomain/index.mdx` - Just like any other domain resource.
2. `/domains/MyParentDomain/subdomains/MySubDomain/index.mdx`
   * You nest the subdomain within the parent domain. (recommended)

Once you have created your subdomain, you can reference it from your parent domain.

### Referencing subdomains[​](#referencing-subdomains "Direct link to Referencing subdomains")

To add a `subdomain` to a `domain` you need to reference the `subdomain` from the `domain` markdown file.

We do this using the `domains` property.

In this example we are adding the `Orders` and `Customers` subdomains to the `Ecommerce` domain.

/domains/Ecommerce/index.mdx (example)

```
---
id: Ecommerce
name: Ecommerce
version: 0.0.1

# List of subdomains (version is optional)
domains:
  # Here version is given, the latest version of Orders Domain is used.
  - id: Orders
    version: 0.0.1
  # Here version is not given, the latest version of Customers Domain is used.
  - id: Customers
---

## Overview

Ecommerce domain contains all ecommerce related information for FakeCompany.

<NodeGraph />
```

Once you add the subdomains to the domain, it will now show in the docs, visualizer and discoverability table.