Bartering allows individuals to trade items that they already have but are not using for items that they need while keeping their cash on hand for expenses that cannot be paid through bartering such as a mortgage, medical bills and utilities. Bartering can also have a psychological benefit because it can create a deeper personal relationship between trading partners than a typical monetized transaction. Bartering can also help people build professional networks and market their businesses.
As Orlove noted, barter may occur in commercial economies, usually during periods of monetary crisis. During such a crisis, currency may be in short supply, or highly devalued through hyperinflation. In such cases, money ceases to be the universal medium of exchange or standard of value. Money may be in such short supply that it becomes an item of barter itself rather than the means of exchange. Barter may also occur when people cannot afford to keep money (as when hyperinflation quickly devalues it).