Mac® Security Bible

1.3. Privacy versus Security

In discussions of computer hardware, software, and networking, the terms privacy and security tend to come up quite often in the same context, and some people assume they mean the same thing. In fact, they're quite different but are closely related.

Privacy is what you have when other people can't find out personal information you want to keep to yourself. When you close a curtain, lower your voice, or cover your hand while typing your PIN at an ATM, you're doing so to preserve your privacy — to keep others from seeing, hearing, or learning things about you that are none of their business. Likewise, on your Mac, your digital information is private when other people can't get at it without your knowledge and permission.

Security is a broader concept. You're secure when there are effective barriers (physical, electronic, psychological, or otherwise) protecting you, your property, or your information in some way. You might put your money in a safe to keep it secure, which means that it's protected from theft. Or you might lock the door of your hotel room to keep yourself secure, which means you're protected from contact with unwanted visitors. Barriers can protect a person from being injured or an object from being stolen — or information from being revealed. In terms of your computer, security encompasses measures you can take to protect your privacy (such as encrypting files and network connections) as well as things you can do to prevent your computer ...