Ṣadaqah is a general term for any charitable act, including:
* Giving money or other possessions to the poor
* Helping someone in need
* Performing acts of kindness
It's a fundamental principle in Islam and is considered an act of worship that brings blessings and rewards.
There is also a specific term for obligatory charity, which is called زكاة (zakāt). This is a fixed percentage of one's wealth that is due to be given to the poor and needy every year.