Strange icon next to the dock

In the past few days I've seen a strange "box" coming up next to the first icon on the dock on some Macs here at the office. The same box can be found in the CmdTab menu.

This happens only on some of our Macs, which have the same version of OS X (10.10.2) and the same AppleID - but other Macs with the same OS X and AppleID don't seem to show the same behaviour.

When the cursor is over the icon, it says "From Mac". The only 2 icons that have appeared there are Chrome and Mail. Clicking the Chrome icon opens a webpage on Chrome that someone else in the office opened recently, and that's a little bit creepy.

I tried to Googling it, but without success... I'm sure it's an AppleID related issue, but I can't find a name for it, and hence I can't disable it.

What is that, and how can I get rid of it?

Solution 1:

This is called "Handoff" and is a feature that Apple introduced with OS X Yosemite and iOS. It is designed to allow you to quickly switch from your Mac to your iOS device but can also work between different Macs.

In this case, it would allow you to switch over to the exact environment that is running on the other Mac. This could be useful if one was working on an iMac, and then picked up their MacBook Air to continue their efforts on a Pages document, for example. Obviously the functionality extends to a number of programs.

To disable, open System Preferences and click General. Uncheck the "Allow Handoff between this Mac and your iCloud Devices" option.

For more information: https://support.apple.com/kb/PH18754?locale=en_US