Micronations — sometimes also referred to as model countries and new country projects — are entities that claim to be independent nations or states but which are unrecognized by world governments or major international organizations. These nations often exist only on paper, on the Internet, or in the minds of their creators.

Micronations differ from secession and self-determination movements in that they are largely viewed as being eccentric and ephemeral in nature, and are often created and maintained by a single person or family group. This criterion excludes entities such as the Republic of China (Taiwan) that have diplomatic relations with other recognized nation-states of the world without being formally recognized themselves by many nation-states or accepted by major international bodies.

Micronations are also distinguished from imaginary countries and from other kinds of social groups (such as eco-villages, campuses, tribes, clans, sects, and residential community associations) by expressing a formal and persistent, even if unrecognized, claim of sovereignty over some physical territory.

Some micronations have managed to extend some of their operations into the physical world by trying to enforce their alleged sovereignty. Several have issued coins, flags, postage stamps, passports, medals, and other items, which are rarely accepted outside of their own community.

The earliest known micronations date from the beginning of the 19th century. The advent of the Internet provided the means for the creation of many new micronations, whose members are scattered all over the world and interact mostly by electronic means. The differences between such Internet micronations, other kinds of social networking groups, and role playing games are often hard to define.

The term "micronation" to describe those entities dates at least to the 1970s The term micropatrology is sometimes used to describe the study of both micronations and microstates by micronational hobbyists, some of whom refer to sovereign nation-states as "macronations".