Most people are familiar with the concept and use of passwords to enter applications or services, and you don't really need to know much more than that to use the Keychain Manager. However, certain important concepts in the Keychain Manager should be clarified.
When trying to find a password, the Keychain Manager searches all unlocked keychains first, starting with the default keychain. If a match is found in more than one keychain, the user might be presented with a dialog box asking them to select the item they want to use.
If a password is not found in an unlocked keychain, the Keychain Manager searches all locked keychains. If the password is found in a locked keychain, the user will be prompted to unlock the keychain so the password can be retrieved. If no match is found in any keychain, the Keychain Manager returns the result code
itemNotFound
and requests user interaction.