> For the complete documentation index, see [llms.txt](https://docs.hollaex.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hollaex.com/hollaex-dashboard/setting-your-domain/frontend-and-backend-domains.md).

# Frontend and Backend Domains

## What Are the Frontend and Backend?

Every website is made up of two main parts: the *frontend* and the *backend*.

The *frontend* is what most people think of as "the website." It's the visual interface that users see and interact with in their browser.

The *backend* is the engine behind the scenes. It's where the actual logic, data processing, and decision-making happen, invisible to the user, but essential to how the site functions.

A helpful way to picture this is a restaurant. The frontend is the dining room: the space customers sit in, designed to look and feel welcoming. The backend is the kitchen: not visible to customers, but where the real work happens.

### What Is an API?

An *API* is the waiter in this restaurant.

The waiter takes a customer's order (a request from the user) to the kitchen (the backend), waits while the kitchen prepares it, and then brings the finished dish back out to the customer.

In technical terms, an API (Application Programming Interface) is what allows the frontend to communicate with the backend, passing requests one way and delivering responses back the other.

This is also why an exchange may use several different front-end domains. One domain is the one the user sees and types into their browser address bar (the "dining room"), while other, separate domains work behind the scenes to process requests (the "kitchen" and the "waiters" carrying orders between them).

## How These Concepts Relate to Your Exchange

When your exchange is first set up, you will be asked to configure two domains: one for the frontend, and one for the backend.

**The backend API domain** is the kitchen half of your exchange. It is not accessed directly by your end users, and will not lead to any webpage that they use. This can be provided by HollaEx, or you can set it yourself.

<figure><img src="/files/pU4v79KDFlU5xIWqQS1g" alt=""><figcaption></figcaption></figure>

**The Project page** is where you set up the frontend half of your exchange, the "restaurant" address that end users actually visit to access your exchange. This domain can be provided by HollaEx, or you can set up your own custom domain by following [these instructions](/hollaex-dashboard/setting-your-domain.md).

<figure><img src="/files/6uHZOdUVSih3C7wD0wVc" alt=""><figcaption></figcaption></figure>

***

## Multiple Projects

Because the frontend and backend are separate, you can create multiple frontends that all draw information from a single backend. This allows you to run different user interfaces, each with different functionality, hosted on different URLs, while only requiring a single HollaEx backend subscription.

<figure><img src="/files/IYbGimfsnunZY2CmYlth" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}
Custom developments provided by HollaEx (such as templates or custom builds) are charged separately from your subscription. If you develop the frontend yourself, this incurs no additional cost.
{% endhint %}