The Keychain is the most dangerous moment of brilliance  ever seen. On one side, it knows your passwords to everything and lets you get away with being human while still being secure. On the other, it lets you get away with being human while being insecure. If you walk away, I can connect to just about any password-protected service you have access to and the computer will fill in the password for me.Yet, it has controls (again, turned off by default) that let you get around this. In Keychain Access, go to Edit and then to Change Settings for Keychain. You can do two things here: set an idle timeout, or tell it to lock on sleep. I prefer just locking on sleep, myself, because I rather depend on the screensaver to do the idle locking for my systems. Sleep, however, especially for portable users, means that the person waking the computer may or may not be the owner, and that’s prime time to start asking for passwords. Until a password is entered you won’t be on IM, or checking mail, or whatever else. Programs that use passwords will be locked from getting new data.

If your keychain password is different from your account password then you have an even greater level of security as the screensaver password won’t work for the keychain, and vice-versa.

http://www.macgeekery.com/tips/security/basic_mac_os_x_security 

Tags: Apple security, creditcard-security, keychain, mac-security, Macintosh security, ox-security