Consider FileVault for Heavy-Duty Protection

FileVault encrypts, or scrambles, the data on your Mac so unauthorized people or software cannot read it. While you are working on your Mac with FileVault turned on, you won’t notice a difference, but everything on the startup disk will be encrypted, safely protected from prying eyes. When you access any of those files, they are automatically decrypted.

Remember, this is an optional security measure. If you don’t have extremely sensitive data on your Mac, you probably don’t need this level of protection.