Handoff works across numerous apps — Apple’s own Calendars, Contacts, Keynote, Maps, Mail, Messages, Notes, Numbers, Pages, Reminders, and Safari apps — as well as some third-party apps.
On your Mac, start by making sure that the feature is enabled. Go to System Preferences → General and make sure the Allow Handoff between this Mac and your iCloud devices box is selected.Then when you come to the Mac on which you’re resuming work, note the icon at the left end of the dock (assuming that the dock is in its default place). Click that icon and you’re good to go.
And if you started work on the Mac and now want to resume on an iOS device, you’ll see the Handoff icon on the Lock screen of that device. Swipe up or double-click the Home button to get going, and from the multitasking screen swipe right until you see the Handoff icon. On the bottom of the iOS device, tap the Handoff strip that appears with a message informing you which app and computer you were previously working on, such as Notes from Edward’s MacBook Air.