This word has come to be synonymous with any organized crime group, though it once just referred to la cosa nostra. Its origins are obscured by time, but I have been told it has two possible origins. One theory it comes from the Arabic word for refuge. The other is it is that is an acronym for “Death To the French Is Italy's Cry”. In Italian that is “Morte Alla Francia Italia Anelia!”.
Given that both the French (Normans) and Arabs have invaded Sicily either is possible.
Most law enforcement groups agree that today's Mafia is a pale shadow of what it once was. Largely due to changes in immigration patterns and the rise of Colombian, Mexican, and Chinese drug cartels as well as the fierce campaigns against them by the Italian and US governments.