Sadaqa is charity given voluntarily in order to please ALLAH.
Sadaqa, also describes a voluntary charitable act towards others, whether through generosity, love, compassion or faith. These acts are not necessarily physical or monetary. Simple good deeds such as a smile, or a helping hand, are seen as acts of sadaqa.
Anyone can give sadaqa for any amount. Some of the companions of the Prophet (peace be upon him) were incredibly generous in giving sadaqa, often giving away large portions of their wealth and keeping only enough to meet their needs. A good balance for us may be to divide our wealth between that which we need, savings and sadaqa.
The Prophet (peace be upon him) would give charity throughout the year but increase his sadaqa during Ramadan. Ibn Abbas (may Allah be pleased with him) said, “The Prophet (peace be upon him) was the most generous of people, and he was most generous during Ramadan” (Hadith, Bukhari).