Mages (魔法使い Madoushi), also known as Wizards, are those who wield Magic of any kind.
Mages are wielders of Magic and they comprise only 10% of the living population. Mages are usually affiliated with a Guild, where they can take Jobs as a source of personal income and adventure. There are two types of Mages in the world of Fairy Tail, Legal Mages and Dark Mages.
Types of Mages
Legal Mages are those who are a part of official guilds and who take legal Jobs. They usually have some sense of justice. They usually heed the words of the Magic Council. These are the Mages people tend to look up to.
Dark Mages are Mages who are a part of the Dark Guilds of the world of Magic. They usually have evil intentions and think little of others, putting their own desires first. These Mages take illegal Jobs and are the main opposition and threat to official guilds and the Magic Council. They are typically dismissive of the legal guilds, viewing their law-abiding ways as restrictive of their full potential. Many dark Mages use dark and sinister Magic types in their fighting style and can be very cruel if not downright insane. Frequently, dark Mages seek out methods of reviving evil creatures and acquiring destructive Magics. Some have even attempted to resurrect Zeref, who was believed to be dead.
Independent Mages (独立魔導士 Dokuristu 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 Earth Land and formerly in Edolas, and they can be used for offense, defense, supporting, and healing. Using a Magic drains Magic Power whether from the Mage or from an external source, with the exception of Edolas Weapons since they used to use Lacrima to power them. Their are two main types of Magic: Caster Type Magic and Holder Type Magic. Within these two there are many sub categories.
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, セカンド・オリジン, 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 is a term used to refer to a Mage who is the head of the guild that he or she is affiliated with. As the heads of their own respective guilds, they virtually have complete authority over their subordinates, and can thus dictate their actions.
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. 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 have been in multiple guilds may be S-Class in their former guild but not their current guild. However, Mages who have achieved the rank before joining their current guild are considered prime candidates to obtain the rank in their new guild. The overall power of S-Class Mages varies between guilds.