Sadaqah is voluntary charity in Islam, given freely and beyond the obligatory zakat, and the word carries a breadth that the English charity does not. Rooted in a term for truthfulness and sincerity, sadaqah is understood as an outward act that verifies the giver's faith. Unlike zakat, it is bound by no threshold, rate, timetable or fixed list of recipients: it may be given at any time, in any amount, to anyone in need, and it need not even be material. A celebrated saying of the Prophet Muhammad extends it to a smile offered to one's brother, the removal of an obstacle from the road, a good word, and the guiding of the lost, every act of kindness, in this teaching, is a sadaqah.
This openness makes sadaqah the everyday texture of Islamic charity, distinct from the formal annual audit of zakat. Where zakat is a due discharged, sadaqah is a continuous disposition, and the two are complementary: the first a floor of obligation, the second an unbounded field of merit.