# Introduction to app-ads.txt support

> Implement the app-ads.txt file on your developer website to declare authorized ad sellers, enhance transparency, and prevent revenue loss from unauthorized inventory.

The [app-ads.txt](https://iabtechlab.com/wp-content/uploads/2019/03/app-ads.txt-v1.0-final-.pdf) file is an Interactive Advertising Bureau ([IAB](https://www.iab.com/)) standard for mobile apps designed to prevent ad fraud by verifying the legitimacy of sellers authorized to monetize a publisher’s inventory.

It protects advertisers from buying invalid traffic and gives greater assurance that their purchases are legitimate impressions from authorized sellers.

The `app-ads.txt` file improves publishers’ ad revenue potential since many advertisers prioritize inventory with verified `app-ads.txt` files. It also helps avoid revenue loss by blocking unauthorized or misrepresented domains.

The `app-ads.txt` file provides the same functionality as [ads.txt](https://iabtechlab.com/ads-txt/), except that developers must host the `app-ads.txt` file in the root of the developer website. Brand advertisers and demand-side platforms (DSPs) scrape this file and cross-reference it when they buy ad inventory programmatically by using exchanges, supply-side platforms (SSPs), and ad networks.

Implement `app-ads.txt` support to combat fraud and create more transparency for mobile advertising. In return, app developers connect with more premium advertisers and higher revenue.

Here are additional reasons to implement `app-ads.txt` support in your mobile app:

* DSPs use this file to understand the supply chain of inventory they buy.
* Some DSPs and brand advertisers only buy from authorized inventories from developers who correctly implement this file.
* Developers who properly declare their authorized sellers help advertisers reduce the risk of counterfeit inventory, which  directs more advertising dollars to quality developers over time.

> **Important:**
>
> Unity Ads requires you to implement `app-ads.txt` to display banner ads. If you don’t implement `app-ads.txt`, banner demand is significantly decreased.