John Dale Beety writes:

What do your characters spend? Currency, the forms of money used in a setting, can add rich and suggestive detail to your worldbuilding. Here are eight key questions to answer when creating fictional currency.

Not necessarily! The word shows up only twice in Andy Weir's The Martian. Currency is irrelevant to the protagonist's lonely struggles.

Because currency is a technology, your setting may not have developed it, using barter instead. Alternatively, post-scarcity societies can render currency obsolete.

While governments usually make and issue currency, other options exist.

Individuals and businesses make private currency, often to fulfill needs governments fail to meet. Religious bodies have issued currency for tithing and other practices. Magic: The Gathering's Orzhov Syndicate combines these phenomena: their alms-coins function like company scrip.

Other currencies aren't issued by central authorities, but are based on consistent rulesets, such as Bitcoin and other cryptocurrencies.

A currency's issuer says it is worth a certain amount. Do others believe that?

Many early coins were commodity money, assuring users that they contained a specific amount of a precious metal, such as the equivalent of 8.1 grams in a gold croeseid of Lydia. Merchants sometimes tested coins and stamped their own approval on them.

Later developments in currency require more trust. Representative money, not worth anything itself but redeemable for something valuable, arose in China a millennium ago. More recently, fiat currencies rely solely on their issuer's reputation.

People spend currency they distrust and hoard currency they do trust, as described by Gresham's Law. Loss of trust can lead to hyperinflation, ruining a currency's value in days or even hours. In Neal Stephenson's Snow Crash, trillion-dollar United States notes are near-worthless. This may seem exaggerated, but real-world hyperinflation once reached the quintillions in Hungary.

To read the complete article, see:
How to Make Your Next SFF Work's Currency(https://www.sfwa.org/2024/02/13/how-to-make-your-next-sff-works-currency/)

As Star Trek would have it, life is so rosy in the future that folks don't have any need for money. (Don't ask us how they get stuff - it's one of Star Trek's fuzzier areas.) The Ferengi, on the other hand, love money - or rather, latinum, a highly precious liquid metal. It's generally referred to as gold-pressed latinum, because it comes inside gold ingots, in denominations of slips, strips, bars, and bricks.

To read the complete article, see:
Star Trek 101: Latinum(https://www.startrek.com/news/star-trek-101-latinum)