How do you define online privacy, and why is online privacy important to you?

Many conversations about Facebook or Google will inevitably elicit comments from people who are concerned about what Facebook/Google “knows about me”. It’s a slow day here on Fluther, and I have decided to ask yet another privacy question. But this time, I’m interested in the following:

1. What do you mean exactly by “privacy”? In other words, is there certain data that falls under the realm of “privacy”? We can all agree that typing on our computer is at least providing one piece of information: we are alive (or pretending to be). It seems that everyone draws the “beyond this line is what I consider my ‘private’ information.” Explain.

2. Are there services you will not use because of your privacy concerns (Facebook, Google, Apple, etc).

3. What types of tools/services do you use to protect your privacy? Do you use an anonymous proxy? Do you merely give a fake name to Facebook?

4. Are your concerns about privacy matters of principle, or do you have good reason to believe that your private information will be used to harm you?