1) zakaatul-fitr is obligatory upon every muslim individual, whether they are young or old, male or female, free or enslaved.

on the authority of ibn 'umar (may allah be pleased with him) who said: ((the messenger of allah (peace be upon him) made obligatory (the distribution of) zakaatul-fitr in ramadan from a saa' of dates or a saa' of barley upon the slave and the free, the male and the female, and the young and the old from the muslims)),

[the authenticity of this narration has been agreed upon by al-bukhaaree and muslim] 

translators note: one saa` is equal to four mudd, and one mudd is equal to the amount held by cupping the two hands together. it is a measure by volume not by weight.

2) the wisdom behind it being legislated: that it be a purifier for the fasting person from that which he may have fallen into from ill speech and sexual intercourse (whilst fasting in ramadan), in addition to it being charity for the poor and needy and the destitute. 

3) the legislated amount: one saa' of:

a) wheat, or

b) barley, or

c) raisins / currants / sultanas, or

d) dates, or

e) cheese, or other than these from that which is considered to be a staple diet.

4) the legislated time for distributing it: the best time for distributing it is before the 'eed (al-fitr) prayer, while it is also permissible to distribute it before the day of 'eed (al-fitr) by one or two days. however, it is not permissible to delay it until after the 'eed (al-fitr) prayer since its distribution after the prayer will be considered as regular charity (and not zakaatul-fitr). 

5) the legislated beneficiaries: it is to be distributed to:

a) the destitute (fuqaraa.);

b) the poor and needy (masaakeen);

c) those employed to assist in its collection and distribution;

d) free the captives;

e) those who have been inclined (towards embracing islam);

f) those who are in debt;

g) for allah's cause (fee sabee-lillaah);

h) the wayfarer (a traveller who does not possess the means to return to his land).

translators note: as a point of reference, one can refer to the qur'an in soorah at-towbah, ayah 60.