Have you ever surf the internet in search for easier means to earn or generate cyptocurrencies?
If you have then you might as well have fallen victim to this tactics.
What's cypto-jacking?
In lay man's terms, it's when your computer generates (mines) coins for hackers. Most people have been and some are still victims to this. It usually happens when you run malacious scripts on your computer, hoping to get easy coins. Unknown to you is the fact that you're making your PC a mining machine to a hacker somewhere. Usually this reduces the performance of your PC because the mining requires a fraction of the CPU and GPU, thus causing your PC to malfunction(though it's difficult to detect this attack) . Depending on the hacker's intention, he could also steal other vital information through this without you noticing.
QUICK GENERAL FIX
Avoid the installation of softwares from untrusted sites. (atimes trusted sites could even be compromised)
Install anti-cyptojacking extensions on your browsers
Avoid opening random links sent to your email by suspicious address
If you can, avoid free mining sites.
These are just few measures that would keep you safe.
Stay safe.