Sadaqah is a general term used to describe charity in Islam. Indeed, all acts of worship through financial / material expenditure are classified as Sadaqah. The Prophet (Peace Be Upon Him) said:
"When a person dies, all their deeds end except three: a continuing charity, beneficial knowledge and a child who prays for them." [Muslim]
Therefore, many Muslims are eager to give charity which will continue to have benefit to people after their death, and continue to earn them reward.