0 a brand name for a system developed by the Apple company that allows users to store passwords, credit card numbers, and other important information safely on their computer, phone, etc.:
Keychain is a type of password management system.
iCloud Keychain stores credit card numbers and expiry dates, passwords and usernames, Wi-Fi networks, Internet accounts, and more.
To lock your Keychain, click the lock icon at the upper left-hand corner of the window.
Either create a new login keychain or update it with your new password.
From the Edit menu in the menu bar, choose “Change Password for Keychain login”.
To use iCloud Keychain, you need iOS 7.0.3 or later on your iPhone, iPad, or iPod touch, and OS X Mavericks 10.9 or later on your Mac.
To keep other people from accessing the information stored in your keychain, set a password for your computer for when it goes to sleep or starts up.
