The word tax is based on the Latin world ‘Taxo’ which means to estimate. Tax means to impose a financial charge or other levy upon a taxpayer on an individual or legal entity by a state or the functional equivalent of a state such that failure to pay is punishable by law. It is imposition of compulsory levies on individuals or entities by government. Taxes are levied in almost every country of the world, primarily to raise revenue for government expenditures, although they also serve other purposes as well. In modern economies taxes are the most important source of government revenue. Taxes differ from other sources of revenue in that they are compulsory levies and are unrequited—i.e., they are generally not paid in exchange for some specific thing, such as a particular public service, the sale of public property, or the issuance of public debt.