Meltdown and Spectre CPU flaws: How to protect your Mac and iOS devices

Surely by now you’ve heard about the Spectre and Meltdown CPU flaws, but you might not fully understand what the issue is and how you can protect yourself against the risks. We’re here to help. Here’s how these vulnerabilities affect your Apple devices and what you can so to keep them safe.Meltdown and Spectre FAQ
One more time, what exactly is the issue here?
There are three separate potential security issues at play here, one named Meltdown and two named Spectre. T