Controlling our Online Identities

How much control do we really have over our online identities? We can make hundreds of profiles in various sites online. We make an identity on each website while we are in the process of making profiles. Each identity is unique in its own way and has its own factors of significance. My amazon identity for instance, is very different from my facebook identity. My facebook identity is very relaxed and informal, my friends and family are used to this nature of mine, because they know me to be a very relaxed person. This personality is what I put forth upon my facebook profile. Therefore, my facebook personality is a similar representation of my real self. My amazon account, however, is very different than facebook. My amazon identity only consists of certain factors about what books I buy, what my tastes are, what I like, how good my ratings are as a buyer and seller, and what books are usually recommended for me. This shows a completely different identity than my identity in facebook.
An issue that arises from all these identities online is do we really have control over them? How can we prevent others from manipulating our identities online? What if there was a friend who writes a negative comment about you on your facebook wall? Would that ruin your positive appearance in front of your other family and friends on facebook who saw that comment?
Many people would just delete that comment and move on with their lives as if nothing had happened. But for many others, it is not that easy to forget, especially to those who saw the nasty comment and changed their impression of you immediately. Your identity is now hurt because of one comment. Similarly, your amazon identity can be hurt if someone gives you only 1 out of 5 stars when rating your seller performance. This would bring your ratings down, and people will not trust you like they did before. Ratings are a big control over our identities on websites like Amazon.com. These ratings tell us what kind of identity a person has.
There are many other controls on websites like Facebook and Amazon. These controls have a grip on our identities that sometimes we have a really hard time letting go of.