It is a positive rabbinic precept to give two gifts for gifts to two poor people on Purim, one gift to each poor person. Even a poor person who himself subsists on charity is obligated in this requirement.
This obligation can be fulfilled through any type of gift: money, food, drink, or clothing. Optimally, the gift should be substantial. If the gift is money, the amount should enable the poor person to purchase bread sufficient for at least one meal. At the very least, each gift must be worth at least a perutah (monetary value of a penny).
The gifts should be given during the day of Purim rather than at night. It is proper to give them after the reading of the Megillah. One should not give these gifts from money which has been set aside for donating to charity. However, one may add a small amount to the money which was set aside and then give the larger amount to the poor so as to fulfill the obligation. Money which one has designated for giving to the poor on Purim may not be given to another charity.
The obligation of giving gifts to the poor on Purim does not free a person from his general obligation to give charity. Even poor people are required to give charity at least once a year aside from their obligation to give gifts to the poor on Purim.
These gifts should be given early enough so that the poor person can benefit from them on Purim and for the festive Purim meal. However, the recipient may use these gifts in any way that he sees fit.
The gifts should not be given before Purim, lest the poor person use them beforehand, in which case the donor will not have fulfilled his obligation.
We do not attempt to determine whether the recipient is indeed poor, whoever stretches out his hand is to be given a gift. If there are no poor people in his community, the gifts which one usually gives should be set aside until he has an opportunity to give them to the poor.