Also spelled 'kafir' or 'kaffir
', Kuffar is a highly derogatory Arabic term used to refer to non-Muslims, though it is usually directed less against "People of the Book" (Christians and Jews) and more against others (Hindus, Buddhists, Shintoists, etc).
Separate laws govern Muslims and kuffars in an Islamic state with kuffars being viciously suppressed. For example: the blood payment to the family of a murdered Muslim man in Saudi Arabia is 1,000,000 Riyals; the payment to the family of a murdered Hindu woman is 3,333 Riyals.
Against kuffars make ready your strength to the utmost of your power, including steeds of war to strike terror into the (hearts of) the Enemy of Allah and your enemy, and others beside, whom you may not know, but whom Allah does know. Whatever you shall spend in the Cause of Allah, shall be repaid to you, and you shall not be treated unjustly. (Qur'an: 8:60)