How does Express handle routes, and what does the '#' do?

How does Express handle routes, and what does the '#' do?

I've setup an Express server using backbone.js with a couple routes, and
I'm trying to capture information through the url using req.params.
I've setup my server with appropriate routing
app.get( '/route/:first/:second', router.routeHandler );
With my express server, when I type in a url like this:
http://localhost:3000/route/firstVar/secondVar
I get raw JSON returned to me, but when I try a url like this:
http://localhost:3000/#route/firstVar/secondVar
it will actually render the html and CSS to the page. What is going on
there? Can I change that behavior? Where is that setup?