Jim Hamm provides this very important information. Before you sell or give away your Mac there are definite steps to take to protect your information that's now on the computer. The article here http://macdailynews.com/2013/08/05/apple-explains-what-to-do-before-selling-or-giving-away-your-mac/ also tells how to return your Mac to its original "out-of-the-box" state. Read this from Apple dated 8-5-13: http://support.apple.com/kb/HT5189