What is the difference between onsite and offsite analytic tools?
I am reading a book about web analytic tools and this is the definition (from the book):
Offsite web analytic's tools measure your potential website audience. They are the macro tools that allow you to see the bigger picture of how your website compares to others.
Onsite web analytic's tools measure the actual visitor traffic arriving on your website.
This doesn't make the distinction clear to me. I generally understand about onsite tools, but offsite tools doesn't make sense.