Where wallets and crypto exchange addresses are concerned, a Whitelist is a list of wallet addresses that you trust.

Trusting an address means you’re familiar with it.

It might be the case that you own it at another centralized exchange (CEX) or with a 3rd party wallet provider like MetaMask.

Perhaps you’ve also manually confirmed the authenticity of the wallet address and you trust it.

Specific to currency exchanges and security best practices, most exchanges allow you to specify a whitelist of IP addresses that are able to interact with your account.

This interaction could take the form of withdrawals, account logins, API access, placing trades, and many other account security mechanisms.

Only IP addresses on your whitelist will be able to perform the specific action.

Whitelists, in this case, can keep unknown actors from accessing your account and potentially withdrawing your funds without your permission.

Specific to ICOs, a whitelist represents a potential investor who has provided their personal information to the ICO administrators in an effort to participate in the ICO.