The meaning of Zakat, Infaq and Shodaqoh
Literally, Zakat means purification, goodness, blessing and growth. Terminologically, Zakat is some wealth when it has reached or exceeded a certain amount that by Allah’s order is to be given to the qualified people. So some of the wealth used to pay Zakat is purified, blessed and growing (QS. 9:103; 30:39). The Zakat payers are called Muzakki.
Infaq is some amount of wealth that is given for certain purposes. Infaq may also be donated to the non-believers (QS. 8:36). A person who gives away Infaq is called Munfiq.
Shodaqoh means true. Terminologically, Shodaqoh is a good deed that includes giving away some of the wealth in order to get a blessing from Allah and as a corroboration of one’s faithfulness to Allah. A person who pays Shodaqoh is called Mushoddiq.
The difference between the three:
Zakat and Infaq are in terms for wealth, while shodaqoh is not always in terms of money, but any good deeds such as a smile or a nice word. Zakat is only compulsory for wealthy people (who have excessive wealth). While Infaq could be an obligatory act as the wealth zakat, it is also a voluntary act for anybody who is wealthy (with excess wealth) or poor (with just enough wealth), as a distinctive feature of a pious person (QS. 3:133-134).