Remote Desktop Shadowing often has a lot of benefits. When helping end users determine problems, it is much easier to see what is going on, what is being slecected and what is being clicked on. While the industry has many products to help with this, such as Bomgar, Webex, or even the free solution join.me, they all require an install.
In secure enviroments, this is not always the best option, and I for one hate to install anything unless I absolutely have to. This leads to Microsoft's built-in functionality in RDS (also know as RDP). In Windows 2012 R2 and Windows 8.1, you may now RDP into another compter with some switches, and watch or even control the session. No extra installs, and it comes built in, and here's how.
I do not shadow others' sessions often. But every so often, I need to shadow an RDP (RDS) session to help out a user, like this morning working with remote site. I have found that Windows 2012 no longer has the Task Manager > users > Shadow option, but thankfully, this was restored in 2012 R2. To get this option, you must install the Role "Remote Desktop Services" and then you can go into the connection window and Shadow, Control, or Control with no notification.