How did people buy things in Medieval Times?

In the early period there was a combination of trading goods (such as jewellery or everyday goods such as sheep hide, wood etc) and coinage. However, with the development of national identities and a solidifying of the centralisation of power coinage was used far more often.

After the Crusades and the establishment of the Knights Templar cheques were used by the ruling classes which later developed into cash cheques which were exchanged for goods and could be exchanged for the relevant amount in gold. (Although this refers more to the Renaissance period).