in-app purchase
Buying digital items or subscriptions inside your app using Apple or Google’s billing system.
Think of buying ride tickets inside a theme park instead of at the gate. In‑app purchase lets people pay for content or features without leaving your app.
It matters because many mobile apps earn money this way. The stores handle payment and fraud checks, and your app unlocks features after it gets proof of payment.
In practice you set up products in the store consoles, the dashboards Apple and Google provide. The app asks the store to charge, the store shows a purchase sheet, and on success you receive a receipt, a proof record you send to your server to verify and turn into an entitlement.