Wordpress is the backend of Wordpress sites.
You can use an FTP connection, but you do not have to have one.
I run WordPress blog, and various installations for clients/development on my server, which has been configured to run PHP (WP is (mostly) PHP). I can log into my wp blog at http://mywpblog.com/wp-admin which is public facing, but only pre login.
Boring (and archaic!) details of my setup, but as you can see I don't need/use an FTP here.
Wordpress offers many solutions (including hosting, development, etc.), as well as can be configured to offer any variety of others...my point is, you don't necessarily have to have any one thing to do this, except for Wordpress.