With economic inequality at an all-time high, some U.S. presidential candidates are proposing dramatic shifts to the U.S. tax code. How have similar plans worked elsewhere in the world?

Relations between the two countries, long bound by common interests in oil and security, have strained over what some analysts see as a more assertive Saudi foreign policy.

China has become Africa’s largest trade partner and has greatly expanded its economic ties to the continent, but its growing activities there have raised questions about its noninterference policy.  …

U.S. and international sanctions have battered the Iranian economy and brought Tehran to negotiate over its nuclear program. Lifting them is central to a deal but will be a complex process.

Hydraulic fracturing has unlocked huge reserves of shale gas and oil, transforming the energy outlook in the United States and the world, even as local opposition and falling world prices threaten th…