We do not sell or share any personal information that you give us, except in the fulfillment of our services to you. (E.g. We need to give the Shipping company an address to ship to).
We use Google Analytics. That allows us to see who visits our website, how often and where they go on our website. It also helps Google serve advertisements for our site.
If you comment on a blog post, some of the details you provide will be shown as attribution to the comment.