A week is a unit of time equal to seven days. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days of worship. Weeks are often mapped against yearly calendars, but are typically not the basis for them, as weeks are not based on astronomy. The modern seven-day week can be traced back to the Babylonians, who used it within their calendar.
The determination of the day of the week for any date may be performed with a variety of algorithms. In addition, perpetual calendars require no calculation by the user, and are essentially lookup tables. A typical application is to calculate the day of the week on which someone was born or a specific event occurred. In numerical calculation, the days of the week are represented as weekday numbers. If Monday is the first day of the week, the days may be coded 1 to 7, for Monday through Sunday, as is practiced in ISO 8601.
In many languages, the names given to the seven days of the week are derived from the names of the classical planets in Hellenistic astronomy, which were in turn named after contemporary deities, a system introduced by the Sumerians and later adopted by the Babylonians from whom the Roman Empire adopted the system during Late Antiquity. In some other languages, the days are named after corresponding deities of the regional culture, beginning either with Sunday or with Monday.
Modern monetary theory or modern money theory (MMT) is a heterodox macroeconomic theory that describes currency as a public monopoly and unemployment as evidence that a currency monopolist is overly restricting the supply of the financial assets needed to pay taxes and satisfy savings desires. According to MMT, governments do not need to worry about accumulating debt since they can create new money by using fiscal policy in order to pay interest.
Zero interest-rate policy (ZIRP) is a macroeconomic concept describing conditions with a very low nominal interest rate, such as those in contemporary Japan and in the United States from December 2008 through December 2015. ZIRP is considered to be an unconventional monetary policy instrument and can be associated with slow economic growth, deflation and deleverage. Under ZIRP, the central bank maintains a 0% nominal interest rate. The ZIRP is an important milestone in monetary policy because the central bank is typically no longer able to reduce nominal interest rates.
