What is a bitcoinminer Trojan?

Could you elaborate on what a BitcoinMiner Trojan is and its potential implications? I've heard it mentioned in relation to cryptocurrency mining, but I'm not entirely sure how it functions or what risks it poses. Is it a type of malware? How does it spread? What are the symptoms of a system being infected? And what measures should one take to protect themselves from such threats? I'd appreciate a concise yet comprehensive overview of this phenomenon.