A tax (also known as a “duty”) is a financial charge or other levy imposed on an individual or a legal entity by a state or a functional equivalent of a state (e.g., tribes, secessionist movements or revolutionary movements). Taxes could also be imposed by a subnational entity.
Taxes may be part of a direct tax or indirect tax, and may be paid in money or as corvée labor. In modern, capitalist taxation systems, taxes are levied in money, but in-kind and corvée taxation are characteristic of traditional or pre-capitalist states and their functional equivalents.
Taxes are usually collected by a governmental agency such as the Internal Revenue Service in the United States. When taxes are not paid to a government’s satisfaction, penalties such as fines, forfeiture, and imprisonment are carried out against the non-paying entity or individual. These penalties are also typically carried out by a governmental agency, such as the Federal Bureau of Investigation in the US. In most modern industrialized countries, when an individual fails to pay his government the taxes that that government demands of him, it will ultimately result in his imprisonment at the hands of the state.
The means of taxation, and the uses to which the funds raised through taxation should be put, are a matter of hot dispute in politics and economics, so discussions of taxation are frequently tendentious.
Public finance is the field of political science / economics that deals with taxation.