Cryptocurrency is the term given to currency such as bitcoin, ether, or any of the other digital currencies out there. So how does this work?
Cryptocurrency runs on what is called a blockchain, a ledger or document that is duplicated over networks of computers. As this is updated, it is made available to the holder of cryptocurrency. Every transaction is recorded of every cryptocurrency. The blockchain is run by miners. Their computers tally up the transactions. They update the transactions and also make sure of the authenticity of the information received. In payment, miners are paid fees for each transaction. The buyers and sellers agree on the value of the cryptocurrency as it fluctuates.
The transactions are made peer-to-peer without a mediator like a bank. The buyer and seller do not know who the other is, but everyone in the blockchain knows about the transaction as they are made public.
If I wanted to buy something that costs $10,000, and find a seller that accepts cryptocurrency, I would try to find out the current exchange rate get the public cryptocurrency address, say bitcoin, and we would stay anonymous to each other. I would then have my Bitcoin installed to his computer, say 10 bitcoins rated at $1000 each. My bitcoin client would sign the transaction with his private key. The transaction would be verified and transferred and recorded.
Coinhive cryptomining scripts were found recently in 19 apps in the Google Playstore. One of the apps had over 100,000 users. They have since been removed from the store.