Webhook / Callback
A mechanism where one system automatically sends a message to another when an event happens, instead of the second system repeatedly asking, used widely for payments and integrations.
Definition
A webhook, or callback, is an HTTP request that one system sends to a URL you provide when a particular event occurs, pushing information to you rather than making you poll for it. In iGaming, webhooks are common in payments, where a provider notifies the operator when a deposit settles or a withdrawal completes, in KYC, where a provider posts back when a verification finishes, and across integrations generally. Because webhooks arrive from outside, they must be authenticated and verified, so an attacker cannot forge a fake payment notification, and handled idempotently, because the same event may be delivered more than once. They make integrations efficient and near-real-time, but they shift responsibility onto the receiver to validate, secure and safely process each incoming message.
Worked example
A player's bank-transfer deposit takes time to clear; rather than the operator polling, the payment provider sends a signed webhook to the operator's callback URL when the funds settle, and the operator verifies the signature, checks it has not already processed that event, and credits the wallet.
Why it matters
For learners, it is how systems tell each other the moment something happens, like a deposit clearing. For professionals, webhooks are everywhere in payments and vendor integrations, and their security, through signature verification, and idempotent handling are common sources of bugs and risk, so they are a key integration skill.