Credit

A credit is a generic term for a monetary unit. Many worlds and civilizations have described their money with the term. While they are not the same system, they often (but not always) refer to a currency system that operates electronically, rather than using currency (i.e., notes and coins).

Examples of monetary systems
The Stoish civilisation, for example, had credits which were stored on "Credit Cards'". The Doctor said that £1,000,000 was equal to 50,000,056 credits in the early 21st century, meaning that the average Sto credit was roughly equivalent to 2 pence. (DW: Voyage of the Damned)

Credits was used in various Human societies. In the 42nd century, in the Second Great and Bountiful Human Empire, the price of an Ood slave was 50 credits. (DW: Planet of the Ood) In the year 200,000, a Kronkburger onboard Satellite Five cost 2 credits. (DW: The Long Game).

The Inter Minorians and Lurmans used credit bars that were blue. One bar represented one credit. (DW: Carnival of Monsters)