You can use decision trees to perform both prediction and classification. Decision Trees are used to make decisions given a set of inputs. The following example will help you understand decision trees:

Assume you go to the market to purchase a product. First, you determine whether you truly require the product; that is, you will only go to the market if you do not already have it. You will determine whether or not it is raining after assessing the situation.

You will only go to the market if the sky is clear; otherwise, you will not.