Nomenclature is a system for naming objects, in this case chemical compounds. A lot of effort has been put into forming a system for unambiguous, systematic naming of chemical compounds. For simple compounds, it works well. As the size and complexity of the chemical compound increases, it becomes increasingly troublesome to work with, and you switch to a simplification in the namine, where entire segments of molecules are named. This way of naming compounds becomes especially common for macromolecules.
Rules for nomenclature are managed by IUPAC, and it is an ongoing development. Therefore, when looking in older educational material, you may find other rules for naming chemical compounds than the ones in force. In practice the old rules still works, and are commonly used, but for exams, you are expected to know the current rules for nomenclature.
Dividing the chemical compounds
How to divide the chemical compounds, when it comes to nomenclature, causes a few challenges, as there is a few grey zones and overlaps in the groups. For the educational material presented here, nomenclature is divided like this: