An enterprise, or cloud application, solves business problems and other real-world problems. These problems cannot be resolved without knowledge of the domain. For example, you cannot provide a software solution for a financial system such as online stock trading if you don't understand the stock exchanges and their functioning. Therefore, having domain knowledge is a must for solving problems. Now, if you want to offer a solution using software or applications, you need to design it with the help of domain knowledge. When we combine the domain and software design, it offers a software design methodology known as DDD.

When we develop software to implement real-world scenarios offering the functionalities of a domain, we create a model of the domain. A model is an abstraction, or a blueprint, of the domain.