If a small business is using Square as their payment processing software, what cloud computing model are they using?

The small business is using the Software as a Service (SaaS) cloud computing model. Here's the step-by-step explanation:

1. Cloud computing is a model for delivering information technology services where resources are retrieved from the internet through web-based tools and applications, rather than a direct connection to a server.

2. This model is divided into three main types: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS).

3. Square, as a payment processing software, falls under the Software as a Service (SaaS) category. This is because SaaS applications are software that's hosted in the cloud, which users can access and use via the internet.

4. In the case of Square, the company hosts the payment processing software and the business owner accesses it via the internet, on a pay-as-you-go basis. This eliminates the need for the business owner to install and run the application on their own computers or in their own data centers, which removes the expense of hardware acquisition, provisioning and maintenance, as well as software licensing, installation and support.

5. Therefore, a small business using Square is using the SaaS cloud computing model.