* This innovative technology had to be:
1) accepted by all
2) the same weight, shape and form for everyone who used it
3) portable (easy to carry)

* The coin ticked all the boxes.
* Let's apply all these parameters to the coins you use every day. If you live in the UK you are used to £1 coins. So let's use £1 as an example

* The first kind of coins were minted in Lydia (modern day Turkey) in around VII century BCE
* Soon coins were used in cities all over the Mediterranean Sea to pay for goods and services

* Coins were used to...
1) pay mercenaries (professional soldiers, who fought for wages)
2) pay for public services (for example: law courts)
3) do business when barter and/or credit were not possible

* silver was the precious metal of choice for drachmas
* the first kind of coin, the Elektrum, was a mixture of gold and silver