Secessionism is the most widely recognised and accepted form of micronationalism, in which an entity claims to be an independent nation or sovereign state but is small enough to generally be ignored by the macronational authorities. In more recent years, the term secessionism has come about in order to distinguish what has historically been the mainstream of micronationalism from simulationism.
The vast majority of external and academic observers of micronationalism use a formal and persistent - even if de facto jocular - claim to sovereignty as the deciding factor to distinguish a micronation from an imaginary country or a geofictional project. That said, a spectrum of sorts can be observed amongst those micronations which would generally be classified as secessionist:
- On one end of the spectrum is what one might call hard secessionists, which would include nations such as Principality of Sealand, Hutt River, and Liberland. Such micronations act for all intents and purposes as smaller versions of macronational secessionist movements, going to great lengths to present themselves as nothing less than fully independent sovereign states. This may often cause conflict with macronational authorities over issues such as taxation.
- Medium secessionists would include nations such as Austenasia, and Ladonia. Although such nations publicly present themselves as sovereign states, they may include some tongue-in-cheek features and may admit "off the record" the futility or impossibility of attaining internationally recognised independence. Adaptations are made to conform with most aspects of macronational laws in order to avoid conflict.
- Light secessionists would include nations such as Molossia and Flandrensis. Such nations officially claim sovereignty, but openly acknowledge their status as micronations and often include satirical or jocular elements.
- Very light secessionists would include nations such as the Republic of Cubia which have a majority of satirical and fictional elements. They are often one-man and have one purpose, and are often made as a joke.
A further form of micronation considered secessionist is that exemplified by nations such as the Principality of New Utopia, the Romanov Empire, and Madrona. Micronations such as these aim to build a sovereign state rather than claiming to administer one, and so although they do not typically claim territorial sovereignty in the present, they intend to do so in the future.
Secessionism is analogue to what is called in Portuguese and Spanish as Derivatismo, or Derivatism, that is, a state that derives from another state. It is often described as a micronation whose claims, including its history, are not fictitious. This term was likely born in Brazil in the 1990s in order to disassociate from the simulationism which is still mainstream in certain parts of Ibero-America. Micronations adherent to this type of micropatriology are called Derivatistas or Derivative.