Push delivers alerts directly to the device of users who have opted in to receive them.
Why it performs
The audience already subscribed, so it's permission-based rather than interruptive — and it reaches users when they aren't browsing at all, which no in-page format can do. That produces high CTR and persistent reach.
Specs
Title 30 characters, body 45 characters, icon 192×192, image 492×328.
Reach: strongest on desktop and Android. iOS web push depends on subscriber opt-in. Pricing: CPC.
Best for: re-engagement, news, finance and dating.
Working within the character limits
30 and 45 characters is genuinely tight. Lead with the specific offer — there is no room for a preamble, and truncated text simply doesn't get read.
Frequency discipline
Push's strength is its intrusiveness, which is also how it fails. Over-messaging drives unsubscribes, permanently shrinking the pool for everyone. Use frequency capping deliberately rather than treating it as an afterthought.
On subscriber quality: push lists vary enormously. Watch conversion rate by source rather than CTR — click rates on low-quality push lists can look excellent and convert at nothing.
Related: How do pop-under ads work, and are they effective? · Is fraud detection and prevention included?