system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the difference between a military, a paramilitary, a militia, and a private army?
gpt
* Military: In context to the question and in modern parlance, a military nationally funded and controlled fighting force, accountable and fully funded by its national government. The purpose of a standing military is as a defense to external threats. Typically, a standing military does not carry actionable authority within a country's borders.

* Paramilitary: A paramilitary is a militarized police force, often partially funded by semi-local taxes. Unlike a standing military, a paramilitary stands only semi-accountable to its national government, and serves as both an enhanced police force and and as a force against both external and internal threats. A paramilitary carries actionable authority within and outside a country's borders.

* Militia: A militia is a body of volunteer citizens, both organized and unorganized. Militias tend to be self-funded and self-organized. Militias are accountable to civilian law, including local, state and Federal statutes. The militia carries actionable authority within a country's borders, where authority is granted to do so.

* Private Army: A private army is a military force which operates independently of governmental structures, and receives its funding from a private source. The purpose of a private army is to extend force for a person or group of people, and a private army's authority is within the funding and scope of a private interest.