The fourth pillar of Islam is the prescribed charity (ZAKAT). Zakat is to donate a portion of special goods and wealth to deserving individuals, according to peculiar priciples. Teherefore, if one gives  a meal to a poor person with the intention of giving Zakat, it is not regarded as Zakat because it is not assigned as Zakat.

The prerequsites that make Zakat obligatory are as follows: An adult, sane, free and debtless Muslim has to have for one year a surplus quantity of productive goods beyond the basic essentials. This amount is called the minimum exemption limit (Nisab). This quantity of goods should also be reproducibe. Gold and silver are not reproducible but their Zakat ought to be given when their quantity reaches the amount of nisab as described below. Nisab: Religiously defined mesurement equal to 82 grams of gold (20 Miskal), or an equivalent amount of Money or trade goods, beyond one’s debts that must be present for Zakat to become obligatory.

One- fortieth (2.5%) of the taxable amount of Money has to be given as Zakat. Zakat on livestock varies according to their type. One sheep for every forty sheep, one sheep for every  five camels, one calf for every thirty head of cattle must be given.
Mines are also subject to Zakat.