Passing is a feature of iPhones, iPads, Apple Watches, and Macs that lets you launch something on one device and then complete it on another device. For example, you can read a web page on your iPhone and then find that you prefer to sit back and read on your iPad or MacBook. With Handoff, the transition is a breeze. You no longer have to write down the URL or mail it to yourself to open it on a second device.
To use handoff, you must meet some requirements. Both devices must be on the same Wi-Fi network, Bluetooth must be on and logged in to the same iCloud account. If you think that your devices meet these conditions, using Handoff is easy. Apple's first-party apps such as Safari, Mail, Messages and Pages support Handoff immediately. Third-party developers can add support for handoff if they believe it is right. Regardless of which app you use, the use of handoff is the same.
First, make sure the handoff feature is enabled. You must activate it on any device you use, including iPhone, iPad, Mac or Apple Watch.
Turn on handover on your iPhone or iPad
Open your Settings app and tap General.
On the General page, tap the Handoff setting.
Press the switch to turn the handoff feature on or off (if desired).
Enabling handover on your Mac
On the Mac, you follow a similar process. Go to System Preferences> General and make sure that the "Allow this Mac to Mac with your iCloud Devices" check box is selected.
Enable Handoff on Your Apple Watch
And on the Apple Watch it's just as easy. However, you must do this in the watch app on your iPhone.
In the Watch app, open the "General" settings and then enable the "Enable Handoff" toggle.
 Now that you've turned on handoff, using this feature is very easy.
Using handoff on your iPhone or iPad
If you need to share something with another device, you do not need to connect Share the sheet and click Submit. You do not need to do anything on the device you're transferring from, unless you need to make sure the app is open and the page or document is loaded. This is because everything about iCloud is kept in sync and instantly available on the target device.
Let's say you've opened a web page in Safari on your iPhone that you want to use on another device. Go ahead and open the page on your iPhone (it does not matter if your iPhone is awake or not). On your iPad or Mac, an additional Safari icon with a small iPhone icon will appear above it. Click to open the page exactly where you left off.
You only need to enter the App Switcher on the receiving device. Depending on whether you use a device with a home button or not, the method is different. When you do, press the Home button twice to do the trick. If you're using a newer device (iPhone X or later, 2018 iPad Pro or later), swipe up from the bottom of the screen and pause.
Once you're in the App Switcher, you'll notice a problem button at the bottom of the screen. The button displays the app that is available to submit, and when it is tapped, it opens the associated app and document.
When you use an Apple Watch, things work a little differently. For starters, you can only pass in one direction: watch to phone. Handover works only with certain apps and Siri. Siri will even offer to automatically post things she can not do on the clock. For example, if you tell Siri on your watch to write an email, she'll automatically resume the action on your phone.
That's really all. You may be surprised at how many apps support handoff these days, and if you need to switch between devices during the day, this feature can save you more time and effort than you think.