Update, May 15: With the Windows 10 Creators Update, Microsoft has largely addressed the forced updates that often resulted in lost work.
And, while the the recent Wanna Cry ransomware does not (thus far) appear to affect Windows 10, you need to make sure your PC is kept up-to-date with security patches to avoid exactly those sort of attacks.
On Windows 8 and 10, hold down the Shift key as you click the “Restart” option in Windows and navigate to Troubleshoot It’s a little more cumbersome than it used to be on the latest versions of Windows, but it’s still reasonably straightforward. Windows Update will recreate what it needs the next time you run it. Return to the Command Prompt window, type the following, and hit Enter: If you’re installing Windows 7 from scratch, you’ll notice that Windows Update will take a very long time while checking for updates.
That's probably why Microsoft has -- controversially -- decided to make Windows 10 an automatically-updating OS.
Windows 10 automatically checks for, downloads and installs new updates to your PC -- whether you like it or not.
Some networks, such as cell networks, are metered by default, but you can also meter your Wi-Fi network by going to Settings Advanced options and turning Set metered connection on.
You can't meter your Ethernet connection through the Settings menu -- Microsoft assumes your Ethernet connection allows you unlimited data, apparently.
If your main issue with Windows 10's automatic updates is the fact that your PC restarts at inopportune times, you're in luck: Windows 10 allows you to schedule restarts for a specific time.
When a new update has been downloaded and installed, Windows 10 will prompt you to schedule a time for your PC to restart.
The only way to set your Ethernet connection to metered is to perform a registry edit -- it's a little complicated, but here's how to do it.
You can still download updates on a metered connection, you'll just have to do it manually by going to Settings Download.
A small warning: Microsoft may be scrapping this ultra-convenient feature in the Windows 10 Anniversary Update.
In the latest Insider Preview build (Build 14342), you can no longer schedule restarts.
But if you -- like most people -- are using Windows 10 Home, you'll need to use workarounds to stave off Windows 10's aggressive automatic updates.