Chrome Remote Desktop is a Google Chrome extension which allows you to remotely access other PCs, Macs, Linux systems, iOS or Android devices, even Chromebooks.
To make this happen you must first install Chrome Remote Desktop on every computer you'd like to remotely access or control.
Choose to enable remote access within the extension and it downloads and installs the appropriate remote access client for you (there's nothing to do here, it all happens automatically).
To prevent hackers accessing your system, it's protected with a PIN number of at least 6 digits.
Once you've done this on all your devices, you can go to one of them - a Chromebook, say - and choose a computer from the list. Enter the PIN number, and that's it, you're viewing the desktop of the remote device, and can launch, run and control programs as though you were sitting in front of it.
By default the remote desktop will be resized to fit the screen of your current device. If this makes it hard to read then you can view it full-size in a scrollable window, instead.
There's also support for sending the PrtSc and Ctrl+Alt+Del keys to the remote system, useful if they don't exist on your current device.
As a bonus, Chrome Remote Desktop also has a screen sharing option. If a friend needs computer assistance and you're both using the add-on, it enables you to access his system, watch what he's doing, then take control when necessary to offer some help.
Chrome Remote Desktop is fairly basic: there's no file sharing, audio streaming, remote printing here, keyboard control and scrolling are limited too. But it's also free, very easy to set up and works almost everywhere, and if your needs are simple then that's probably good enough.