Google requires me to post a privacy policy on my website.
They want you to know that some of your moves are being monitored (is anyone surprised?) After all, Google is the expert when it comes to optimizing webpages for the viewer's "user experience".
And it works. From their search engines to their online blogs, Google is the best as far as relevancy goes. I have even found ads in my dashboard, meant for me, that were scary in their relevancy. They all were just what fit. (Can google read minds?)
So please don't think that Google is collecting personal data on you to spam you out or something. They just want to be sure that the ads you seen on my page fit what you want. That's all.