Back in 2006, Jeff Lindsay proposed a different way of consuming Web resources that would eliminate the need for constantly polling APIs for changes. This new pattern was called webhooks and has since been adopted by companies such as GitHub and Google.
REST and webhooks are two sides of the same coin. In “Web Hooks and the Programmable World of Tomorrow“, Jeff Lindsay, October 2008
The main advantage of the webhooks pattern is that your application doesn’t have to make periodic calls to APIs while it’s waiting for changes. Instead, APIs will call your application on a specific endpoint informing that something interesting has happened. What’s missing is a way to programmatically tell APIs that you’re interested in receiving calls and registering endpoints.