Webhooks simply POST data (or JSON) to a specific URL every time we see something new. Webhooks can also accept data (or JSON) to kick off a workflow in Zapier.
You can find more information here.
Poll a URL and look for new entries.
Wait for a new POST, PUT, or GET to a Zapier URL.
Wait for a new POST, PUT, or GET to a Zapier URL. Only retrieves raw request body (max 2 MB).
Poll a URL and look for new entries. (May improperly dedupe items.)
Poll a URL and look for new entries. (May improperly handle XML XPATH.)
Fire off a single PUT request as a form or JSON.
Fire off a single POST request as a form or JSON.
Fire off a custom request by providing raw details. Very flexible but unforgiving.
Fire off a single GET request with optional querystrings.