Website Log in and WP Log in

I am currently researching Blogs for my company and I am leaning towards Word Press. What I am wondering, is their any way that I can tie my company’s website log in with Word Press. Like most websites, when a user registers to a site they create a user name and password. Can I make it so when a user registers with my company’s site, it signs them up for our Word Press with the same username and password for our site? Is this possible and how?

Currently from what I understand about Word Press, is users have to sign up for the blog when they want to post or become a user of the blog.Any feedback is greatly appreciated.