Fitr means to break fast or to refrain from fasting. Hence the Eid after the fasts of Ramadhaan is called Eid al-Fitr, as it marks the completion of fasting. On this occasion of happiness, as a sign of gratitude one has to give a specific amount in alms, which is called Sadaqatul Fitr. This is to purify and obtain complete blessings for the fasts of Ramadhan. Please note: It is Wajib to give Sadaqatul Fitr.