Measurement
Pixel
A snippet on the advertiser's site that reports visitor actions back to the advertising platform from the browser.
What makes it wrong.
The mechanism, not the warning.
A pixel that fires on a page rather than on an action counts page views as conversions. This inflates every downstream number and is invisible in the platform, which reports what it was sent.
In detail.
The pixel is the browser half of conversion measurement. It builds audiences, records events, and feeds the optimisation models that automated bidding depends on.
It is also the half most affected by tracking prevention, ad blocking and consent choices, which is why the server-side path exists alongside it.