Cryptojacking is a relatively new threat on the Internet. By the term we refer to websites that take advantage of their visitors' computing resources to mine cryptocurrencies.
So if you happen to suddenly slow down your computer while the work you are doing does not justify it and your system fans are speeding up in an attempt to cool the device components, something happens… and you have probably fallen victim Cryptojacking. 
That is, someone smart uses your computer resources without informing you…
This is also the main issue with cryptojacking: it is done without the knowledge of the users. Various websites load scripts that allow the use of your computer's resources by its "smart" administrator σελίδαs.
Pages using such scripts obviously do so for monetization. One of the benefits of this latest fashion tendency is that it happens in the background and does not hinder the layout or content of the site.
Of course there are extensions for browsers that hinder these scripts, but there are others which contain them in a hide and work in the background just like the scripts mentioned above.
Opera Software was the first browser manufacturer to offer protection against Cryptojacking in its browser.
Opera Software engineers have created a site you can visit to check if you are protected by new fashion (Cryptojacking).
Visit just the site and do click on the Start button. THE application it will test your browser and show you the results, along with the blue button that allows you to download the Opera browser.
Opera Software displays a total of test scores on the site, and 74% of all users are protected by Cryptojacking according to the statistics of the page.
Users who use unprotected browsers and do not want to use Opera can install some extension that protects them from Cryptojacking.. They can also use some security software which protects against these scripts. But they can also disable JavaScript on untrusted pages.
