You hear a lot these days about online privacy, the main concerns seem to boil down to:
1) People you don’t know having access to your personal information
2) People taking your “identity” and using it for bad purposes
3) Websites building “profiles” of you and tailoring their services around information you don’t want them to have
These are valid concerns, of course, and mainly revolve around people you don’t know getting personal information about you and using it.
There’s also another concern, illustrated by a grad student’s discovery 15 years ago that 87% of Americans can be identified with only their birthdate, sex, and zip code. It’s an interesting story and you can find it here. The concern is that someone you’ve trusted with information (knowingly or unknowingly) can link it to other information they have and get personal information about you.
I’ll give you two examples:
1) Online surveys: If you’ve ever taken an online survey and entered your email address (for instance to be entered for a prize), its very simple for someone to look at each of your individual answers based on your email address. More nefariously, if you send survey invitation emails through a service like SurveyMonkey, they create a unique link for each email address. Thus, even if you don’t enter your email address, the person giving the survey can still see which answers YOU gave.
2) Website traffice statistics: Let’s use my blog and my dad as an example. Let’s also say that I want to see how much my dad really loves me, which I’m going to judge based on how many times he checks my blog.
I track the visitors to my website using Google Analytics. My dad lives in Anderson, SC, and I’m pretty sure that noone else living in Anderson is checking my blog. So, I just sign in to analytics, set the date range for this year, and check the traffic detail for Anderson. So, dad, just how much do you love me?
In the case of the internet, you’ve often got to choose between the greater of two goods (or the lesser of two evils), balancing privacy and relevancy, safety and convenience, anonymity and personal interaction.