The Keychain stores all your information to use encrypted disk images and to log onto file servers, FTP servers and Web servers. Mac OS X automatically adds your .Mac account information to your Keychain. When you log in to Mac OS X, the system opens your Keychain. You don't have to enter your user name and passwords to access this data. You can set Mac OS X to lock your Keychain when the system sleeps or is inactive for a time. The system will ask you for your password the next time you try to access secure data. Other users on the system cannot access your Keychain or its data.