Handoff is Apple's new feature that integrates Yosemite and your iOS 8 device so you can start working on one device and then continue it on another. For example, you can start writing an email on your phone, then flip it over to your Mac when you realize you'd prefer a keyboard. Here's how to set it up and use it.
Enable Handoff in Yosemite
Before you get started actually using Handoff, you'll need to go through a few settings to make sure everything is ready to go. You'll also need a Mac that's compatible.
Head to System Preferences (Applications > System Preferences).
Turn on Bluetooth
Go to General
Check the box marked "Allow Handoff between this Mac and your iCloud Devices"
That's it for Yosemite. Now you'll need to get over to your iOS device and set it up there.
Enable Handoff in iOS
You'll need to change a few settings in iOS to use Handoff.
Open up the Settings app
Turn on Wi-Fi
Turn on Bluetooth
Head to General > Handoff & Suggested Apps and toggle Handoff to On
Now, provided you're on the same Wi-Fi network as your Mac, handoff should work. You don't need to actually pair your iOS device with your computer over Bluetooth, they just both need to be on.
How to Actually Use Handoff
With everything set up, you can start using handoff. Right now, it only works with a handful of Apple apps, including Mail, Safari, and the Calendar, but using it is very simple.
How to Send Something from Your Mac to your iOS Device
If you want to send something over to your iOS device from your Mac, just start working in one of the compatible apps on your Mac. When you're ready to open it up on your iOS device, check out your lock screen. You'll see an icon for the app. Swipe up to open it there.
How to Send Something from your iOS to you Mac
If you're working on something on your iOS device and want to open it up on your Mac, you'll see a new icon pop up in your Dock with the app you can open. Click the icon, and it'll open it up.
Likewise, if you get an incoming call on your iOS device, you'll see a notification pop up on your Mac to answer it. Click the answer button to answer right there, or the dropdown menu to deal with it later.
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