Barter is a system of exchange where goods or services are directly exchanged for other goods or services without using a medium of exchange, such as money. It is distinguishable from gift economies in many ways; one of them is that the reciprocal exchange is immediate and not delayed in time. It is usually bilateral, but may be multilateral (i.e., mediated through barter organizations) and, in most developed countries, usually only exists parallel to monetary systems to a very limited extent. Barter, as a replacement for money as the method of exchange, is used in times of monetary crisis, such as when the currency may be either unstable (e.g., hyperinflation or deflationary spiral) or simply unavailable for conducting commerce.