Must read: Hot or Cold?
A hot wallet is any wallet that has an active connection to, or is hosted, on the Internet. These wallets are more abundant than cold wallets and are often more user friendly. Thanks to their connection to the Internet, moving funds in and out of these wallets is quick and easy. Unfortunately, this ease of use also comes with disadvantages, such as making them susceptible to hackers, phishing scams and other vulnerabilities. Examples of hot wallets include those offered by exchanges or web wallets such as MyEtherWallet.
A cold wallet refers to any wallet stored offline. Cold wallet storage can refer to a number of methods, such as creating a paper wallet with a QR code, storing a wallet on an air-gapped computer (disconnected from the Internet) or using a hardware wallet. While considered more secure than a hot wallet, cold wallets are often slow to use, require a physical object and can be damaged in ways hot wallets cannot. Hardware wallets are a particular type of cold wallet, popular for their additional security and redundancy features.
Find out more about the different types of cryptocurrency wallet.