Alternatively, you can press Command-Tab to bring up the Mac's application switcher. If an app can be handed off, you'll see its icon to the left of the switcher. Select it and the appropriate app will launch.
Handoff on an iOS device
On an iOS device you'll see evidence of Handoff on the lock screen. When an app is available for handing off, you'll find its icon in the bottom-left corner of the screen. Swipe up on it, enter your passcode, and the appropriate app will launch on your device and display its current content.
You needn't quickly lock and unlock your device just to access Handoff, however. You can also double-click the Home button to get to the multitasking screen and swipe to the right. The first pane you see in this screen is used by Handoff (see the image at the top of this page). Tap it and the correct app will launch.
In either case you can continue to work within an app and then hand it back simply by invoking Handoff on the original device. Or, if you like, hand it off to yet another compatible device within range that shares your iCloud address.
Note that the device you're handing off from must be awake and unlocked. If, for example, you're working on an email message on your iPhone and that iPhone automatically locks, Handoff won't work until you wake the phone and unlock it.
And that's Handoff in a nutshell — a convenient way to get your work done from whatever device is best for the job.
Sign up for CIO Asia eNewsletters.