Explain Zone in Angular?

In Angular 6, Zone is used to detect when certain async operations occur to trigger a change detection cycle. Zone.js is an execution context that helps developers intercept and keep track of async operations. Zone works on the concept of associating each operation with a zone. Each zone can fork and create a child zone with a different context, no limits. Inside a zone, async operations are captured using different APIs, so that the developer can decide what to do with the interceptions.