Impressions are the number that reflects each time an ad was served. It’s counted by SDK callback onShown() at the moment when ad is being displayed, regardless of whether it is actually viewed or clicked.

Views are the number of complete impressions. It’s counted by SDK callbacks:

Video and Rewarded Video: by onFinished() callback, when ad is fully displayed.

Native and Banners: 1 and 2 seconds after onShown() callback.

Static Interstitials: by onClosed() callback.
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To read more about Impressions, check out our blog post.