What is a "Hooligan"? and what do "Hooligans" do?

A Hooligan is a thug or ganster, normally a child as opposed to an organised adult criminal. Im not sure of the eytomology of the word but the "Gangstar" Defintion probably comes from the "Hooli" prefix as its seen in all types of types of the word for example "Hoodlum", "Hooligun", "Hooligans" etc.