How to password protect applications on Mac?

I think this similar method is the best solution yet:

If you need to leave a long-running render running, but don't want anyone to mess with it, enable 'Fast User Swiching'. Then when you need to walk away and let it render, click the 'Fast User Switching Icon' in the menubar, and log in anew (without logging out of the running rendering) as Guest, or a similar Account you have set up.

Then no one can mess with or see your stuff, Guests can have access, and your Rendering keeps running.

OS X Yosemite: Switch quickly between users

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Aloha all, I get it, where is the apple computer protection, like app or in app file locks\passwords, sure share the laptop but until all are as enlighten as I, mind your own business. Like pages I want to be able to pour out facts and lock the door on it but if some one else is using or snooping like all girls do, they can still use pages but have to come to me for the password..... where is this function?

As has been stated multiple times by multiple posters in this long thread, Mac OS X does not offer the exact feature you are asking for. It offers protection for ALL your files, but in a different way.

Give your girlfriend her own Account, and she will have full access to all the Applications but will NOT be able to access any files you created on your account. Do not leave the computer logged in to your Account with an unlocked screen when you step away from it. This effectively locks not just all the running Applications, but all your emails and every other document on your Account. Those kinky emails from Fifi will be unreadable as well.

This is because Mac OS X is already built as a Multiple-User system, and provides very good protection from other Users and Guests if you simply create additional another accounts (or use the Guest account) and take advantage of the many protective features already implemented.

If you have a specific situation you would like addressed, please start a new thread with a title that will attract the readers you want to discuss your distinct requirements.

If you just "me too" on the end of this long thread, without reading and thinking deeply about the solutions already presented, Readers are unlikely to be patient or kind to you.

I stumbled on this (old) thread while looking for a solution to the same problem. After some more searching, I found iLock. There is about a 2 second delay on my computer before starting any app that has been locked with it, but it allows the user to select which apps to lock and seems to work well.

http://www.osxbytes.com/ilock.html?forcedownload

This actually is the only way to pass protect an app for free.

You are so right.