Service workers are a fundamental part of a PWA.
They enable fast loading (regardless of the network), offline access, push notifications, and other capabilities.

BROWSER SUPPORT FOR Service Workers

1. Chrome version 4 to 39 doesn't support Service Workers. Chrome 40 to 44 partially supports Service Workers. Chrome 45 to 67 supports Service Workers.
2. This element is not supported by Mozilla Firefox browser version 2 to 32. Service Workersis not supported in Mozilla Firefox browser version 33 to 43 by default but can be can be enabled in Firefox with the dom.serviceWorkers.enabled flag. Service Workers is supported in Mozilla Firefox browser version 44 to 61.
3. IE browser version 6 to 11 doesn't support Service Workers.
4. Safari browser version 3.1 to 11 doesn't support Service Workers. Safari browser version 11.1 supports Service Workers.
5. Microsoft Edge browser version 12 to 14 doesn't support this property. Service Workers. Microsoft Edge browser version 15 to 16 doesn't support this property. Service Workersby default but can be enabled. Available behind the 'Enable service workers' flag. Microsoft Edge browser version 17 supports this property. Service Workers.
6. Opera version 10.1 to 26 doesn't support Service Workers. Opera version 27 to 31 partially supports Service Workers. Opera version 32 to 53 doesn't support Service Workers.