Currently, Quirks are classified into five general types - Emitter (E)/(M), Heteromorphic, Transformative, Accumulative, and Meta. In the current era, most Quirks can be categorized as at least two of the five.
Emitter (E)/(M) - Emitter Quirks themselves are further broken down into two sub categories, E and M for Energy and Matter respectively. These quirks are abilities that primarily allow the user of the quirk to generate and sometimes control certain things, or alter the conditions of things around them. The vast majority of Emitter type quirks require conscious effort to activate however that is simply the norm, and other activation methods have been documented in all Activation Tags. Emitter Type quirks often have a variety of ranges dictated by the strength of the user and the actual manifestation itself.
While most Emitter-type Quirk users generally have a handle on their own "emissions", it's also possible for users to hurt themselves from coming into too much contact with their Quirk as they gradually lose their natural resistance to the harmful aspects of their quirks. In the case of Accumulative hybrid Emitters, generating too much of their emission or doing so for too long can potentially harm the used if their own stock is formed from their body.
Emitter-type (E) Quirks are the most common type of Quirk, followed by Emitter-Type (M) Quirks as the second most common.
Heteromorphic - Heteromorphic Quirks, or as they are more crassly referred to as Mutant Quirks, are Quirks that generate a permanent 'abnormality' directly related to their powers. Often times, Heteromorphic Quirks will bestow prehensile appendages that the user can control, or alter the physiology of preexisting limbs to enhance their capabilities. While not exactly a weakness, Heteromorphic Quirks cannot be deactivated, and can cause their users inconveniences due to their non-standard body types. On the other hand, due to the far more physical nature of these quirks, they are partially immune to many Meta quirks, most notably Cancellation type effects which they are fully immune to. Since Heteromorphs are so distinct, they are the most identifiable at a glance. One further issue in the current day is that many heteromorphs are the subject of discrimination due to their outer appearances. Interestingly, Heteromorphic quirks show the least common manifestation of alternative methods of activation such as those documented in Activation Tags. Because of this, there is a theory that Heteromorphic Quirks evolved separately from the Golden Baby.
Heteromorphic Quirks were historically the least common type of Quirk, but given the genetically dominant traits that many heteromorphs show, it is likely that over time this type of quirk will become the most common.
Transformative - Transformative Quirks are those abilities that cause the user to take on a temporary alteration of some kind, such as temporarily enhancing existing features, removing existing features, or creating entirely new features to the body all together. Many transformative Quirks require conscious effect by the user to activate, though many users can be trained to initiate them reflexively. That does not mean that alternative activation methods do not exist, though the commonality of such are lower for Transformative quirks than Emitter types. The overwhelming majority of Transfromative Quirks require a close range proximity to be able to fully utilize them in combat, due to how the quirk can only affect the user's body. However these quirks are quite often very powerful, and their biggest weakness beyond the range limitation is the fact that their effects are temporary in nature, and over-exertion can lead to painful backlashes. Transformative Quirks are the most common type of quirk to have hybridized with Accumulative quirks over the years, and as such there are a great number of Transformative Quirks that require a resource to reach their full potential.
As of the current age, Transformative Quirks are the third common type of Quirk.
Accumulative - Originally, this category of quirk was entirely separate from the other manifestations of Quirks. These quirks involved the building of a stock of whatever particular manifestation that was related to the quirk, and the usage of the quirk would rely completely on the stock. Often times, these quirks were seen as being very weak and were disparaged by the societies in the past. However, in the current day most Accumulative Quirks are hybrid quirks that have taken on aspects of the other classifications of quirks enhancing the capabilities of the other aspect of the quirk. Emitter quirks that rely on a stock of energy can be used for longer and with less stress on the user because it is not their own energy that is being used to power the effect, but the stock. Transformative quirks that have stocks can be used for longer than those that rely on the strength of the user alone.
Accumulative Quirks are considered rather averagely spread among the populous. Neither common, nor uncommon.
Meta - The Meta classification of quirks is the most recent development within the science of registering and understanding quirks. Meta Quirks have been theorized to have existed for as long as any other type of quirk, but due to the complex nature of their abilities, this classification has gone ill-documented over the years. Meta Quirks are those abilities that allow the user to manipulate the usage and limitations of quirks, both their own and those of others. The most common type of Meta Quirk are Self-Regulating Quirks, those abilities that have multiple different modes and activation types that can be shifted between at the expense of the other modes. Sundrop is an example of a Meta Quirk, who can enhance her own strength and durability at the cost of losing flight and ranged capabilities. Another type of Meta Quirk are Cancellation type quirks, that allow for the user to prevent other quirk users from using their quirks. The least common type of Meta Quirk are Replication type quirks, that allow for a user to replicate the abilities of those around them.
Meta Quirks are by far the least common type of Quirk.
Activation Tags - A short-hand for the method by which the quirk is used. The most common tag is ME, or Mental Effort, followed by FFA, or Five-Finger Activation.