Lesson 4; Managed Infrastructure. As discussed previously, Cloud providers offer a console which allow customers to manage a suite of Cloud computing services in almost what could be said as a self-service type of a model. There are three major categories for Cloud computing: Software-as-a-Service, sometimes called SaaS, Platform-as-a-Service, and Infrastructure-as-a-Service. Each of these categories consists of a large set of service offerings such as software application, computing models, development services, and more. Software-as-a-Service is a very popular Cloud service. Firms purchase Software-as-a-Service, also consumers purchase Software-as-a-Service. QuickBooks can be an example of a consumer using a Software-as-a-Service product. Software-as-a-Service products are hosted by the third-party Cloud provider and then made available to users over an Internet connection, and Software-as-a-Service is a method for delivering the software products based on subscription model. Therefore, even with products, very complex enterprise software such as salesforce.com or ServiceNow, the user or the customer only pays for a subscription and does not take on the overhead of maintaining and upgrading the software. That's all done by the Cloud provider. With a Software-as-a-Service, firms are only charged for the time and the software products that they're using, so they can be charged by the user and by the product. Again, making Software-as-a-Service much more efficient than maintaining the software on-premises. Platform-as-a-Service is another popular Cloud offering and is a another part of the categories of Cloud services. Platform-as-a-Service is typically involved in the development of software without the complexity of having to install and maintain developer environments or developer platforms. Platform-as-a-Service includes networking, virtual servers, storage, operating systems, middleware, and runtime database, and other types of services that a shop may use to develop applications. A Cloud provider could maintain operating systems such as mobile such as iOS or Android. Quite often, these types of operating systems change quite frequently and it's a lot for a single firm to keep up with all of that whereas a Cloud provider specializes in that area and can always offer the best type of mobile development operating systems or mobile development environments. They can also offer release type of tools for the firm. So therefore, the firm doesn't have to make a big investment on release and deployment type of tools. Infrastructure-as-a-Service is another popular category in Cloud computing. Infrastructure provides a basic layer of computing. It resembles a typical outsourcing model. So a firm instead of employing specialist in hosting database, networking, hardware, it does not need to do that with a Cloud, the firm can or the customer can outsource all of those specializations to the Cloud provider.