To put it simply a webhook is an event that triggers an action.
In your app, you would consider a webhook to be a customer redeeming a promotion, once a customer has redeemed a specific promotion, that will trigger an action.
Some actions that webhooks may be use for include:
- Sending an email or SMS to a customers to reach out after they have redeemed the promotion - "Hey xxxxx, Thanks for redeeming xxxxx, we can't wait to see you in store"
- Email or SMS customers with a unique voucher code for an external loyalty system
- Subscribe customers to a VIP mailing list