A class is one part of a title assigned to a player, the other part being aspect. There are twelve known normal classes and two "master" classes, making 14 known classes in total. Classes describe the intended role of a particular player in Sburb, and how they can use their aspect.
A few class mechanics have been explicitly explained, others only implied.
Connections to Culture
The 12 classes seem to be connected with Swiss psychiatrist Carl Jung's mythic Archetypes, as such, the classes' passive/active alignment seem to be more likely connected to it.
Passive and Active
The classes come in passive (+) and active (-) pairs, with each member of a particular pair performing a similar function but with differences in execution and outcome. It is a vague concept with some flexibility. For example, both Rogues and Thieves steal. However, Rogues do so to help their teammates while Thieves do so for their own benefit. Various guidelines of the dichotomy have been revealed from a simplistic "active means offensive, passive means defensive" to more complex ones with the active classes employing or affecting their aspect directly and for their own gain, and the passive classes being affected by their aspect and sharing their actions with the team.
The passive/active system exists on a scale with classes being more passive or active than others. With the exception of the master classes, no class' position on the scale has been revealed, although some hints have been given. The passiveness or activeness of a class is one of the multiple factors related to whether a player is a Prospit or Derse dreamer.
All the classes have different gender alignments, with some of the classes tending to be assigned to both males and females, with others being exclusive to a certain gender. While not all the gender alignments are known, there are equal numbers of male exclusive and female exclusive classes. So far three male exclusive classes (Bard, Prince, and Lord) and a single female exclusive class (Muse) have been confirmed. Out of the remaining ten classes, five are known to be assigned to both genders (Knight, Rogue, Thief, Seer, and Mage) although some of them have a bias towards a certain gender, and the final five have only been shown assigned to a single gender but unconfirmed to be gender exclusive (Heir, Maid, Page, Sylph, and Witch). Given the unbalanced numbers at least two of the remaining five must be female exclusive (presumably Witch and Maid because of their feminine connotation), with the remaining three (Heir, Sylph, and Page) all assigned to both genders or split between gender exclusive and gender biased.
Thief and Rogue
Thief and Rogue are a pair of classes, respectively active and passive. They are assigned typically, but not exclusively, to female players. They deal with the redistribution of an aspect. While the active Thief will steal, or take their aspect for themselves, the passive Rogue will generally distribute it to someone or something outside of themselves after taking it.
The exact powers of the Heir class are unknown and are up to reader interpretation. Whether the class is active or passive is also unknown. The gender alignment for the class appears to prefer males, but whether or not the class is male exclusive is unknown.
The only known Heir is Jentha Briati, the Heir of Light.
The exact powers and definition of a Maid are unknown.
The only known Maid is Calder Kerian, the Maid of Void.
The exact definition of the Page class is currently unknown, as is its passive/active alignment, though it is hinted that the class "provides others with [aspect]" or "creates [aspect]".
Pages seem to have a tendency to begin their sessions with a personal deficit in their aspect.
The only known Page is Sovara Amelie, the Page of Heart.
The Knight is a class assigned to both male and female players. The exact powers of a Knight are unknown, but they have been shown as warriors that exploit their aspect as a weapon. It is unclear where they fall on the active/passive axis.
The only known Knight is Laivan Ferroo, the Knight of Space.
The Seer is a passive (+) class, assigned to both male and female players, that uses extensive knowledge to coordinate their team members. They understand their aspect comprehensively. Seers will also keep their party from making grave mistakes as if they had a strategy guide imprinted deep in their mind. The knowledge of offshoot timeline outcomes is fully within their domains.
The only known Seer is Albion Shukra, the Seer of Hope.
The exact definition of the Mage class is unknown, as is its passive/active alignment. The Mage class is assigned to both males and females.
The only known Mage is Ellsee Raines, the Mage of Life.
The Sylph is a magic-based class that is thought to specialize in healing. Its placement on the passive/active scale is unknown, although it is heavily speculated to be passive (+).
The only known Sylph is Tazsia, the Sylph of Rage.
The Witch is an active (-) class. The exact definition of the Witch class is unknown.
The only known Witch is Serpaz Helilo, the Witch of Doom.
Bard and Prince
Bard and Prince are a pair of classes, respectively passive (+) and active (-), that are exclusively male and deal with destruction. The Prince, as the active, is literally simplified to "destroyer of [aspect]" or "one who destroys via [aspect]". Bards are somewhat stranger, in that they "allow the destruction of [aspect]" or "invite destruction through [aspect]". The Bard is also quite the wildcard, unpredictable by nature and thus equally likely to help or hinder his party, often to great effect. In extreme cases, they are single-handedly responsible for their party's massive downfall, their improbable victory, or sometimes even both.
Princes, it seems, are devoid of their aspect. Due to their nature as the destroyer class, it stands to reason that they destroy their aspect in themselves.
Muse and Lord
These two classes (the so-called master classes) are significantly more powerful than the others. The Muse is female-exclusive and the most passive (+) of all classes, while the Lord is male-exclusive and the most active (-). Presumably, these classes are paired.
It could be speculated that these classes deal with interference at a cosmic level.
It could also be speculated that the muse class is based on the traditional role of a Muse, to inspire.
Progressing as a Lord involves excruciating effort and a large amount of suffering.
In fact, taking all of the above points together, it may be suggested that the two master classes are at least partially codified by the ability of the player to influence events indirectly: the Muse inspires others' actions despite not being in a position to do anything directly by herself, while the Lord instructs his minions' actions in the places he cannot reach.
It is possible that these classes are "master classes" in the sense that they are "master copies," or guidelines for what defines active and passive classes. Alternatively, it could also be presumed that the lord holds the combined roles of the active (-) classes, while the muse has the roles of the passive (+).
There are currently no known Muses or Lords.