When you browse the web, sites know your IP address. Consequently, I'll know your IP address. The only thing I'll do with it is to anonymously track page usage statistics to know which pages are more popular than others, in what order visitors visit them and where visitors come from. I won't share your IP address with others.
If you send me an email, I'll have your email address and will add it to my address book. However, I won't share your address with others.