An attempt to explain the Spanish system
First of all, it is important to note that there is no standardized, international system for awarding hotel stars.
In most European countries, hotels are classified by an authority or a professional association. In Germany, for example, the classification of accommodation into 1 to 5 stars and the addition of superior is regulated by a points system of the DEHOGA / Hotelstars Union. A comprehensive catalog of criteria determines the number of stars.
In Spain, classification is prescribed by law and is implemented decentrally by the 17 autonomous communities according to different classification laws. As a result, the quality criteria applied vary throughout Spain. The classification ranges from luxury, first class, comfort, standard to tourist.
Hotel signage
The classification can be recognized by a sign in the entrance area. There are stars or keys and letter combinations. The "Q" seal of quality guarantees that the hotel has undergone a voluntary inspection. An "S" stands for Superior - as a little more than the stars shown but not yet sufficient for the next higher number of stars.
Orientation option: Abbreviations
Hotels (H): Single or shared rooms. 1 star to 5 stars
Aparthoteles (HA): An apartment hotel is accommodation with furnished apartments that are rented out to vacationers. They consist of a kitchen, bathroom and either a living room and bedroom or a separate living and sleeping area. 1 star to 5 stars
Apartamentos Turísticos (AT) or Apartamentos: A vacation apartment that is rented out to vacationers. It consists of a kitchen, bathroom and either a living room and bedroom or a separate living and sleeping area. 1 key to 3 keys and luxury (4 keys)
Hostales (HS): Accommodation with mixed or same-sex dormitories with 4 or more beds, but also single and shared rooms. Often also youth hostels. 1 star to 3 stars
Pensiones (PE): Guest house with single or shared rooms. 1 star to 3 sta
Paradores (PA): Paradores de Turismo de España: Usually stylish accommodation, often with historic buildings and therefore also state-owned. 1 star to 5 stars
Turismo rural (TR): Casa rural (country house), Alojamiento rural (rural accommodation), Hotel rural / Posada rural (rural hotel). 1 star / key to 4 stars / key
Fondas (F): Simple hostels