You have a Mac and possibly another Apple device, such as an iPhone, iPad, or Apple Watch. If you have started a particular task on one device and want to continue with another, you can do this with handoff.
This feature allows seamless transitions between your devices. Start an email, text message or other item on your Mac and continue it on your iPhone. Start a task on your iPhone and continue it on your iPad. You can even start a task on an Apple Watch and continue on your iOS device.
Handoff works primarily with Apple apps such as Safari, Calendar, Contacts, and Podcasts, but it also supports third-party programs. On the operating system side, Handoff OS X requires Yosemite or higher on Mac, iOS 8 or higher on iPhone or iPad, and watchOS 1.0 or higher on Apple Watch. On the hardware side, the feature requires at least iOS devices and Macs, but they all support Apple Watchs.
To use Handoff, each device must be connected to the same Wi-Fi network and logged into iCloud with the same Apple ID. How to set up Handoff and use it.