Islamic digital currencies must refrain from a number of actions deemed prohibited by Islamic law, in contrast to traditional cryptocurrencies like Bitcoin. They cannot entail interest-based transactions (Riba), undue speculation or uncertainty (gharar), or gambling (maysir). Their frequent backing by physical assets, such as gold, gives them inherent stability and lessens the speculative bubbles that are typical of traditional cryptocurrencies, which is what makes them so intriguing.