The term "pegged" is used to describe a currency whose value is fixed to the value of another asset, generally a currency or commodity. Typically, the peg is requires a person or organization to guarantee that the currency can always be exchanged for the underlying asset.
This is a big requirement of trust and cryptocurrencies don't work well with trust.
Lots of professional traders went bust when the Swiss government decided to remove the pegged floor to the Euro. So you will have to be certain about the peg and the person/institution guaranteeing the peg.
