The denarius was the Roman silver currency commonly used during the Republic.
Rome introduced the denarius around 211 BCE, during the Second Punic War. It was initially valued at ten asses, a relationship reflected in its name, which derives from the Latin word for ten. The coin typically carried a portrait or head on one side and a Roman deity, personification, or military scene on the other.
The denarius remained a major Roman coin for centuries, although its weight and silver content changed. Under the early Empire, it was especially important for military pay, taxation, trade, and everyday accounting. Roman writers also used denarii when describing prices and wages.
The aureus was a gold coin, not the standard silver denarius. The sestertius was originally a smaller silver denomination but later became a large brass coin used frequently as an accounting unit. The solidus was introduced much later by Constantine.