What is mapping?
“an operation that associates each element of a given set (the domain) with one or more elements of a second set (the range).” in terminology.
Where should we use mapping in real life?
Usually, when the request is completed, we receive the data in various formats. I choose JSON in examples below. These data formats should be converted to our models in our app. So that we will be able to use them as we want and in accordance with OOP. And those custom classes will let you code your model businesses in your custom classes.