Cryptojacking is the practice of secretly installing software on a user computer without their knowledge to mine cryptocurrencies.
Cryptojacking was once only possible through viruses and malware, but it has evolved to the point where modern cryptojacking can occur right through a user’s internet browser.
In some cases a website owner will intentionally place code on their servers that causes the computer of any visitor to their site to mine cryptocurrencies, but in some cases the software is covertly installed on web servers.
It is also possible to cryptojack users through display ads on a website, with the cryptojacking code being installed directly within the advertisements HTML code. It has been estimated that there are over one million web sites that have been cryptojacked, although it is impossible to verify the truth of this.