In macroeconomics, crawling peg is an exchange rate regime that allows currency depreciation or appreciation to happen gradually.
The system is shaped to peg at a certain value, but at the same time is designed to "glide" to respond to external market uncertainties.
It transitioned from a fixed exchange rate in the 1990s without the instability of rapid devaluation.
For instance, if there are substantial currency flows that may affect the exchange rate, monetary authorities may be "forced" to accelerate currency realignment, leading to substantial unsystematic costs to market players.
The delayed peg uses a wideband for exchange-rate fluctuations, while the band is allowed to move when foreign exchange liabilities accumulate (at a secret but predetermined rate).