Provisional Sinn Féin evolved from the split in Sinn Féin and the IRA that took place in the late 1960s. The leadership of both Sinn Féin and the IRA had developed a Marxist outlook that became unpopular with many more traditionalist nationalists/republicans who formed Provisional Sinn Féin and the Provisional IRA in repsonse.
The remainder of Sinn Féin became known as Official Sinn Féin which itself subsequently evolved into the Workers Party.
The modern political party Sinn Féin is that of Provisional Sinn Féin. For a fuller history see the article: Sinn Féin.
