Sinn Féin is an Irish republican and democratic socialist political party in both the Republic of Ireland and Northern Ireland.

Irish republicanism is the political movement for the unity and independence of Ireland under a republic. Irish republicans view British rule in any part of Ireland as inherently illegitimate. An ideology since the 17th century, various methods have been employed to achieve the republic, including rebellions and paramilitary campaigns. Although the makeup of republicanism has been multidenominational, its relation to catholicism increasingly became central.