JavaScript tools allow cryptojackers to harness the CPUs of phones, tablets, PCs and servers. They use this collated power to validate cryptocurrency transactions before other miners. The reward for providing this service comes at someone elses expenseand that someone, whether an individual or organisation, often has no idea their processing power has been hijacked. 220 sites on the Alexa top 100,000 list serve crypto mining scripts to more than 500 million people, generating a collective $43,000.”]
Source: https://www.csoonline.com/article/3249502/why-cryptojacking-overlooked-security-threat.html