Cold storage is a method used to keep cryptocurrencies safe from the threats of online attacks. It involves storing the private keys that allow access to your cryptocurrency holdings in a way that keeps them disconnected from the internet. This could be done through hardware wallets, paper wallets, or even air-gapped computers. While cold storage is not as convenient for frequent trading or transactions, it provides a much higher level of security, making it ideal for long-term holders and investors who want to protect their assets from cyber threats.