localhost
is nothing except a different name for the IP address 127.0.0.1
. localhost
is not software. I assume that your system is executing IIS; that is the server in your system. When you pay a hosting provider they are using a server such as IIS or Apache and their computers are always on. You can configure a domain's DNS to know to use the hosting provider's version of your website. If you are using the application in a website configured in your local IIS as a website then it should work the same in an IIS implementation in a hosting provider.
Correction: Visual Studio provides a developer version of a web server and uses it for running websites developed using VS. For the purpose of understanding hosting providers, the VS server is the same as an IIS server in an IIS hosting provider.
Have you used Azure? You can create an account for free. You can create a website for free that does not use a custom domain (such as www.example.com) but that you can see how your application works in an IIS hosting provider. Then if you want to use a custom domain for it then that will cost a little bit but the application will work the same; you just need to configure the DNS to know to go to the website when someone browses to the domain.