Activate a Sharing Only Account on Your Mac
Your Mac comes with a pre-established Guest User account. This account lets friends or clients use your Mac temporarily, but nothing they do is saved on your Mac, although it could be saved to a Shared file or to a remote storage site like Dropbox or an external hard or flash drive.
By giving someone a Guest User desktop to use, your Desktop and everything you’ve so neatly organized doesn’t get poked around or messed up.
Your Mac has only one Guest account because multiple users will access the same Guest account. To enable the Guest account, follow these steps:
Choose Command→System Preferences, and then click the Users & Groups icon.
If the lock icon in the lower-left corner of the preferences window is locked, click to unlock it and then type your password in the dialog that appears. Press Return to unlock your Mac’s user account details.
Click the Guest User icon that appears in the list box on the left to open the Guest User dialog, as shown in this figure.
Select the Allow Guests to Log In to This Computer check box, which allows anyone to use your Mac’s Guest account without a password.
(Optional) Click the Open Parental Controls button if you want to specify which programs guests can use (or not use) and whether they can access the Internet.
(Optional) Select or deselect the Allow Guests to Connect to Shared Folders check box.
If this option is selected, a Guest account can read files created by other accounts and stored in a special shared folder or the other users’ Public folder.
Click the Close button of the Accounts preferences window.