How Do I show the change of data on the same webpage using PHP?

I am building a food ordering website like FoodPanda as a project. Now among all pages , I have my order screen which will have two parts. On one side it will show the food items , clicking on which will add the items to my cart and on the other side I will show my cart. Now, what I want to do is I want to show the items added on my cart as soon as I press a button which will add them and show it in the same page without refreshing the webpage. How do I achieve this?