Zakat is paid on 5 types of properties; cattle, gold and silver, commercial goods, grains and fruits and mineral resources. Each has its conditions. Those who neglect paying it are promised a painful suffering.
Zakat is one of the 5 pillars of Islam. It is a charity duty imposed on a certain threshold of excess money and paid to the poor. It is the most important pillar after testifying that there is no deity than God and prayer.