Regardless of where and how you build an IT system - the production of (good) software is not cheap and possible changes - often more expensive than it seems at the beginning. In fact, reworking the same piece of code does not motivate the work of programmers, which reduces their commitment and efficiency. Today's users are very demanding and if they do not like your product right away, there is a risk that they will abandon it forever.
Prototyping is a construction of a mock-up of the application that will look like your application, will behave like your application ... but will not be an application (it will be a visual representation of how your application works). Another important feature would be the fact you can build basic models in a few hours, while an implementation of a program that presents similar functionality will allocate more time and resources. This model of cooperation allows you to test the user experience before an actual (much more expensive) solution is created, while guaranteeing that the money you have invested has been managed efficiently.