> For the complete documentation index, see [llms.txt](https://support.happydemics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.happydemics.com/methodology/happydemics-respondents/audience-retargeting.md).
# Audience retargeting
In some cases—depending on the media and setup of your campaign, it’s possible to **target respondents likely to have been exposed to your campaign**. This can be done by providing us with **exposure data** such as tracking pixels, user IDs, broadcasting framework or geolocation data. You can go to the dedicated section for more information.
That said, **exposure targeting is entirely optional**. Even without it, we’re able to gather a reliable sample of **250 respondents who recall seeing or hearing your ad** and 250 who don’t. This split allows us to measure the impact of your campaign using our methodology.
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