Customers access the applications over the internet.
In contrast to the traditional client-server model of implementing and maintaining applications entirely on the customer's facilities, the application hosting model enables companies to run applications without incurring the capital or personnel overhead of a complex computing infrastructure. The ASP and its IT staff build and maintain the computing infrastructure hardware, software, and networking. All the customer needs is a web browser for each user, so it's easier to make the applications available to many more people in the organization. You can be up and running with a complete internet infrastructure in much less time. The infrastructure is likely to be more reliable, flexible, and secure than the in-house alternative.