# External Demand Sources

External demand sources enables you to connect to a Supply-Side Platform (SSP) in order to fetch programmatic ads client-side or server-side. If you are a publisher with programmatic revenue, this may be a feature that enables you to increase revenue by auctioning your direct inventory against programmatic inventory, and earn the highest revenue cross-channel for every ad impression.

![External demand source setup example](/files/-LSFNFBJmpGUUi0Zmrzd)

{% hint style="info" %}
This is the first step to set up programmatic ads. After you have completed these first steps, move to [External ad units](/adnuntius-advertising/admin-ui/inventory/external-adunits.md) to set up connections between each Adnuntius ad unit and your SSP ad units.
{% endhint %}

**Name and description**: Give the connection a name and description (optional) of your choice.

**External demand source**: Choose your demand source. Please note that if you choose prebid, then this is all you have to do - you do not have to complete the step below.

**Publisher ID**: Type in the publisher ID that you receive from your SSP account. Once this is done, Adnuntius connects to your SSP server-side.


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