Hi and sorry if my post looks silly but I think I must now use a password when I turn on my iMac on ML 10.8.4. True I never used one cause I'm the only user of the iMac. But a friend made me aware of identity and data theft if my computer was stolen and I'm freaking out right now. Better late than never. Here it is: I've had my late 2012 iMac since July. So I am the administrator. I have a system wide username and password set when I set up the iMac on the first day. But I don't enter any password when I start a new session or when tie iMac wakes up from sleep. Went to Security pref pane and also googled "Security" but I'm lost in translation. Too many info in a single moment. May I ask you the short route to using a password at start-up. I would appreciate to be able to use my admin password. Is it possible? Again, sorry for the newbie attitude. Cues are apprediated. Cheers.