This is for the benefit of John McCain, who otherwise would not know the difference:

The Shi’a adhere to the Quran and teachings of the final Prophet of Islam, Muhammad, and in contrast to other Muslims, believe that his family, the Ahl al-Bayt (the People of the House), including his descendants known as Imams, have special spiritual and political rule over the community.[2] Unlike Sunni Muslims, the Shi’a believe that Ali ibn Abi Talib, Muhammad’s cousin and husband of his daughter, Fatimah, was the true successor to Muhammad who was appointed by God and his prophet, and thus reject the legitimacy of the first three Rashidun caliphs.

Examples include: Grand Ayatollah Seyyed Ruhollah Musavi Khomeini, Sheik Ibrahim al-Amin, Hassan Nasrallah, Mahmoud Ahmadinejad, Grand Ayatollah Ali al-Sistani, Hizbollah.

Salafis view the first three generations of Muslims, who are Muhammad’s companions, and the two succeeding generations after them, the Tabi‘in and the Taba‘ at-Tabi‘in, as examples of how Islam should be practiced…

The principal tenet of Salafism is that Islam was perfect and complete during the days of Muhammad and his companions, but that undesirable innovations have been added over the later centuries due to materialist and cultural influences. Salafism seeks to revive a practice of Islam that more closely resembles the religion during the time of Muhammad.

Examples include: Muhammad ibn Abd al Wahhab, Abdul-Azeez ibn Abdullaah Aal ash-Shaikh, Usama bin-Laden, Al-Qaeda.

Salafis don’t get along with Shi’ites very well. Something John McCain does not have a clue about.