What is a referring URL?

I was under the impression that a referring URL was the blog who visited your blog? Is that not what it is? I'm new to this, any help is appreciated.
It's the url from which the visitor clicked a link to your page. It can be a url on your website or on a different site.
referring URL is something like who referred your website or more like "who sent the visitor to your website" or "From where the user is redirected to your website"
Take an example
you shared your website's link on facebook & from there, if somebody clicks on the link on land on your website then here FACEBOOK is referring URL.