Such a very good information. Some get really creative in storing their keys. Some have them engraved on steel then stored in a safe, some encrypt them in music files, while others have them tatooed on their skin. But as we know, the most commonly found in the loss of bitcoin or altcoin is human error. just enter a private key into an airdrop form and an application that contains trojans or malware that is eventually embedded in the pc. be careful in using tools or applications because of the RAT is not really good. And keep your coin from being stolen by others.