Categories will help you to classify your questions and to be divided into different topics. When creating a question you can specify categories to be assigned to the question. You can use also the categories to search specific questions via . A category is represented as a folder and has its functions. There are shortcuts to the questions in the categories. You can add subfolders to a main category (category root), thus you'll have more categories.

Please, note that the category root folders are determined by your pAdmin.