Mages (魔導士 Madōshi) are individuals who can wield Magic of any kind.
Mages are wielders of Magic, using their Magic Power to cast spells and employ magical objects. They comprise only 10% of the living population of Earth Land, with the remaining 90% being either incapable or unwilling to use Magic. They are often affiliated with a guild, where they can take on Jobs as a source of personal income and adventure; according to Lucy Heartfilia, Mages can't be considered full-fledged until they join a guild of their own choosing. There are three main types of Mages in the world of Fairy Tail: Legal Mages, Dark Mages and Independent Mages.
Types of Mages
Legal Mages are those who are a part of official guilds, take on legal jobs and usually heed the words of the Magic Council. These are the Mages people tend to look up to, with the most famous of them having the chance to be featured in the Sorcerer Magazine.
Dark Mages (闇魔導士 Yami Madōshi) are Mages who are members of Earth Land's illegal Dark Guilds, guilds which are not aknowledged as such by the Magic Council, having either lost their rights due to crimes, or having never been affiliated with the Council in the first place. They are guilds that the Council refuses to recognize. After being deprived of the Council's approval, guilds are ordered to disband, and, if they do not abide to such order and keep functioning, are then categorized as Dark Guilds, becoming known to all intents and purposes as criminal organizations. In collective imagination, Dark Mages usually have evil intentions, think little of others, putting their own desires first, and can be very cruel, if not downright insane. These Mages are said to take illegal Jobs and are reputed as the main opposition and threat to official guilds and to the Magic Council itself. Many of the Dark Mages introduced so far are typically dismissive of Legal Guilds, viewing their law-abiding ways as restrictive of their full potential. Frequently, Dark Mages seek out methods of reviving evil creatures and acquiring destructive Magic to carry out their shady plans; some of them have even attempted to resurrect the legendary Zeref, who was believed to be dead 400 years ago.
Independent Mages (独立魔導士 Dokuritsu Madōshi) are Mages that are not officially recognized by the Magic Council and don't belong to either Legal Guilds or Dark Guilds, instead being part of the so-called Independent Guilds.
Magic (魔法 Mahō) is the main form of combat for Mages, and is bought and sold all throughout the world. All kinds of Magic are used in the dimension of Earth Land, and they possess many avenues for usage, such as offense, defense and supporting. The Guild Master of the Fairy Tail Guild, Makarov Dreyar, went on to describe Magic not as a "miracle," but as the power to overcome "reasoning" stemming from "reasoning" itself, claiming that the "spirit" flowing within Mages and the "spirit" flowing within natural connections form an embodiment. He also added that for this process to become true and thus for Mages to use Magic, a strong mentality and a lot of concentration is needed.
Employing any Magic drains Magic Power whether from the Mage or from an external source, with the exception of the former items which were present in the dimension of Edolas, since they used to be powered by Lacrima.
Magic Power (魔力 Maryoku) is the energy which allows Mages to employ Magic, and it is composed of Ethernano. Every Mage has a container inside their body that determines the limits of their Magic Power. In the case that it becomes empty, Ethernano comes from the atmosphere and enters the Mage's body: after a while, their Magic Power is returned to normal. However, recent studies have identified another part of Mages' Magic container that isn't used normally and contains their dormant power, called Second Origin (二番原 Sekando Orijin). If the power within this second container is reached, then the Mage in question will receive an enormous boost in Magic Power, allowing them to wield more powerful spells and to use their Magic over longer periods of time.
Guild Master (総長 Masutā) is a term that refers to a Mage who heads a guild, effectively acting as the guild's leader and highest authority. As the rulers of their respective guilds, they have virtually complete authority over their subordinates, and, thus, can dictate their actions. Guild Masters are also tasked with maintaining amicable relationships between guilds in every province, something achieved through the various provincial leagues of Guild Masters, gathering from time to time in regular meetings, where Masters report about their guilds. Above Guild Masters, within the magical hierarchy, are members of the Magic Council, who supervise all guilds.
S-Class Mages (Ｓ級魔導士 Esu-kyū Madōshi）are elite members of a guild, and usually number among the most powerful individuals in the guild itself. Only officially recognized S-Class Mages are able to undertake difficult S-Class Jobs; lower-ranked Mages may only accept an S-Class mission if an officially recognized S-Class Mage is also participating alongside them. These missions are said to be so dangerous that even the smallest mistake can lead to the Mage's death. However, in return, the pay is very good, easily going into millions of Jewels.
In the Fairy Tail Guild, one must go through a trial and compete to obtain the rank of S-Class. Eight participants are chosen every year by the Guild Master to take part in the trial, and the one who comes out on top is awarded the title of S-Class. The competition is often fierce and difficult, and doing so opens up more difficult and higher paying missions for the Mage. More than strength is important in being selected as an S-Class candidate: heart and brains matter as well.
The S-Class rank from one guild does not necessarily transfer over when a Mage joins a new guild, so S-Class Mages who change their guilds might not retain their past rank, partly due to S-Class levels varying from guild to guild, and some guilds not having any official distinction between stronger and weaker members. However, Mages who have achieved the S-Class before joining their current guild are considered prime candidates to regain the lost rank in the new guild.