There is no evidence to give definitive proof as to when money first came into existence. But many historians and professionals who work as a Coin Dealer such as those from GM Coins have seen evidence of metal objects that were used as currency. The first ones are thought to have come into existence as far back as 5,000 BC.
Before money was developed goods were acquired by bartering. Individuals would offer one item in order to be given another. Bartering still exists in some places today but it is centred around haggling on the amount of money that is paid for an item.
It is thought that the Lydians were the first people in the western world to design the money that we would recognise as coins. It was not long after this that coins were made of different values and used to buy products. This has carried on throughout history.
Since these early days money has also been used as a way of displaying wealth, with those people who have more money being those who are elevated to the higher levels of society and those with little money in the lower levels. Money was then used as a way to reward people who completed certain tasks and this is how the concepts of work for salaries came into existence.