--- title: "What Is a Webhook? Plain Definition | Nexum" description: "What is a webhook? A plain definition for business readers: how it works, how it differs from polling and an API request, and what makes one reliable." url: https://nexumautomations.com/glossary/webhook updated: 2026-10-31 publisher: Nexum Automations, an AI consulting firm --- > Nexum Automations is an AI consulting firm that builds what it recommends. It finds where AI pays off in a company, builds it on the tools the team already uses and stays until it is live and working. Glossary # What is a webhook? Explained A plain definition of a webhook, how it works, how it differs from polling and an API request, and what makes it reliable. Last reviewed October 30, 2026 Definition Webhook A webhook is a message one app sends automatically to another app's web address the moment an event happens, such as a payment clearing or a contract being signed. **In short:** An automatic message sent when something happens. Our data ## What buyers see in this search The first page of Google for "what is a webhook", counted by type of result. | | Results | | ---------------------------------------------------- | --------------------------------------- | | Articles by companies that sell a product or service | 4 of 7 | | Forums and Q&A threads | 1 of 7 | | Independent publishers and explainers | 1 of 7 | | Social and blog-platform posts | 1 of 7 | | Titles that answer this exact search | 7 of 7 | | Google features on the page | An AI Overview, People also ask, videos | The 7 organic results on the first page of Google, United States, desktop, measured with DataForSEO on October 29, 2026\. Types only: no company or product is named. Side by side ## Webhook vs polling vs API request Three ways to move data between apps. | | Webhook | Polling | API request | | --------------- | ------------------------------- | ------------------------------ | ---------------------------- | | Who starts it | The source app | The receiving app | The app that needs data | | When data moves | When the event happens | On a fixed timer | When someone calls | | Wasted calls | Few | Many empty checks | None, calls are deliberate | | Delay | Near instant | Up to one interval | Instant when called | | Example | Paid invoice triggers a receipt | Checking for new orders hourly | Looking up a customer record | ## What is a webhook in plain words 1. Event Something happens, like a payment clearing. 2. Message The first app packs the details. 3. Delivery It sends them to a set web address. 4. Action The second app does its next step. If you wonder what is a webhook, think of a doorbell. Nobody walks to the door every minute to check for visitors. The bell rings when someone arrives. Red Hat describes a webhook as a lightweight, event-driven way to send data between applications over HTTP. The sending app does the work. The receiving app just listens. The webhook meaning for a business: when a payment clears, a form is filed or a contract is signed, the next system hears about it right away. ## How a webhook works * Event A payment clears or a form is filed. * Payload The data that describes what happened. * URL The web address that receives the message. * Receiver The app that acts on it. Four parts are involved. The event is what happened. The payload is the data about it, such as an amount or a customer name. The sending app delivers that payload in an HTTP request to a URL you gave it. The receiving app then acts, for example by updating a record or sending a confirmation. You set it up once. After that, nobody has to keep asking whether something new has happened. ## Webhook vs polling and API requests Polling * The receiver keeps asking * Checks on a timer * Most checks find nothing new Webhook * The source sends the news * Data moves when the event happens * No empty checks Red Hat explains polling as a client sending requests at regular intervals until the server returns the data. A webhook flips that. The source pushes the data the moment something happens. An API request is a one-off call that asks for or sends data when you choose. A webhook needs no ask. For the wider idea of connecting systems, read [system integration](https://nexumautomations.com/glossary/system-integration). ## Business uses and what makes a webhook reliable Good practice * Retry failed deliveries * Verify each message's signature * Keep logs on both sides Risky setup * Trust any message that arrives * Drop a message on first failure * No record of what came in Webhooks suit anything that should react the moment something happens. A signed contract can start onboarding. A cleared payment can update the books and send a receipt. New forms can open tasks. Red Hat notes webhooks can launch event-driven automation for IT actions too. If you want help wiring apps together, see our [AI integration](https://nexumautomations.com/services/ai-integration) work. Reliability depends on three habits. The sender retries when delivery fails. The receiver checks a signature to confirm the message is genuine. Both sides keep logs of what arrived and what did not. * Retries when delivery fails * Signature checks on every message * Logs of what was sent and received FAQ ## Webhook questions * ### What are webhooks used for? Webhooks pass news between apps as it happens. A cleared payment can update the books, a signed contract can start onboarding, and a filed form can create a task, all with no one checking by hand. * ### What is a webhook vs an API? An API is a set of rules for asking an app for data or sending it, when you choose. A webhook is the app calling you when an event happens. Many setups use both. See [API integration](https://nexumautomations.com/glossary/api-integration). * ### What are webhooks in simple terms? A webhook is an automatic alert between two apps. When something happens in the first, it sends the details to a web address the second app listens on. The second app then reacts. * ### Are webhooks secure? Webhooks can be secure, with care. Good setups verify a signature on each message, accept only expected senders and log every delivery. Without those checks, anyone who finds the address could send fake events. * ### What happens if a webhook fails? A well-built sender retries the delivery several times. If the receiver is down, the message waits and tries again. Logs let your team see what failed and replay it. Read about [electronic data interchange](https://nexumautomations.com/glossary/electronic-data-interchange). --- Source: https://nexumautomations.com/glossary/webhook Free AI diagnosis (30-minute call): https://nexumautomations.com/#book - Services: https://nexumautomations.com/services - Guides: https://nexumautomations.com/guides