It is the liquid extracted from an apple and all its components, that is then boiled to concentration. The liquid can be extracted from the apple itself, the apple core, the trimmings from apples, or apple culls. It is typically opaque due to fine apple particles in suspension and generally tangier than commercial filtered apple juice, but this depends on the variety of apples used. Cider is typically pasteurized to kill bacteria and extend its shelf life, but untreated cider is common. In either form, apple cider is seasonally produced in autumn. It is traditionally served on the Halloween, Thanksgiving, Christmas, and various New Year's Eve holidays, sometimes heated and mulled.