This paper highlights some salient technical and economic features of the management of frequency and voltage ancillary services across various jurisdictions (the North American NERC, the continental European UCTE, Australia, Belgium, California, France, Germany, Great Britain, the Netherlands, New Zealand, PJM, Spain and Sweden). Vocabulary used to designate active power reserves are first described and classified into a common framework. Policies related to selected technical features of ancillary services, as well as some particular aspects of the procurement methods are then compared.