It is iCloud tabs, which lets you automatically open up tabs that had open on another device. And it is actually very simple to do. Lets say you have productivity pad open on your Mac, but you want to read it on you iPad, here is what that would look like.
|You have this webpage open on your Mac...|
|...and now you do on your iPad too|
Here is how you do it on an iPhone:
And a Mac:
As long as you are signed into the same iCloud account on all your devices you shouldn't have an problems.
To check on a Mac just go to: Apple menu> System Preferences > iCloud > account details. Also make sure that the Safari box is checked. As in the video below.
This makes it very easy to switch from one device to another without having to remember and type in complicated URLs. The only problem you will run into is with password protected sites, you will have to put in your login info again on the new device.
Well I hope that helps. It is a simple tip that can save you a lot of time. Thanks for reading, and remember, live better.