Many Internet companies now believe that they own user data and can do with it what they please. Turns out that this is a mixed blessing. Good for them if they collect advertising revenue from your browsing habits. Good for you if you want to be targeted by companies whose products interest you. This PC Advisor article provides a fair statement of the pros and cons of the data privacy discussion.
SXSW: Is Browser Tracking and Data Harvesting Good or Bad? - PC Advisor