The Keychain Security feature, which was introduced in Mac OS 9, enables you to create a keychain file where you can store passwords and certificates for servers, applications, and Internet locations. Once you open your keychain, you can access any location for which you have saved a password or certificate without manually logging on.
For example, say you access a certain file server every day. When you open the file server, you're prompted to enter your Name and Password. If you store this logon information in a keychain, when the keychain is open, you can access the server without going through the logon process.
The Keychain Access feature can save a lot of time if you access many secure items.
To create a keychain ...