The price chart for crude oil has looked like a water slide in an outdoor pool over the past year and a half. It has been a fun ride for many, while others will nurse their bruises for some time to come.
Oil dropped below 40 dollars a barrel in December, down from a peak of over 100 dollars in June 2014.
Here's a look at how this trend is affecting people, industries and countries in the global economy.
Consumers: People save money as fuel becomes cheaper. In Germany, diesel intermittently dropped below the 1-euro mark per litre towards the end of the year, and heating oil hit a six-year low.
"The oil price decline is like a big tax reduction," said Peter Brezinschek, chief analyst at Austria's Raiffeisen bank. In addition, the oil price slump keeps inflation in check.
Manufacturers: Industries that use a lot of energy or oil will continue to profit, analysts say. This includes steel and machinery makers, pharmaceutical companies and producers of chemicals.
Meanwhile, consumers have more money to spend on durable household equipment, Brezinschek said.
Lower oil prices also help to keep costs down in the transport and aviation sectors.
Industrialized economies: The European Union, the United States and other industrialized economies gain from cheaper oil imports and from stronger consumer demand.
"The recovery is becoming broader and is being driven by consumption rather than exports," European Central Bank chief Mario Draghi said in December, pointing to low oil prices.
Germany's economy, for example, can save up to 20 billion euros (21.9 billion dollars) in energy costs per year, says Claudia Kemfert, the chief energy expert at the German Institute for Economic Research in Berlin.
Emerging economies: Emerging countries that are net oil importers also reap benefits. This includes China, India and Turkey.
However, there is also a downside. "A low oil price helps with economic development, but it also hampers the shift towards alternative fuels or towards better energy efficiency," Kemfert said.
Oil exporters: The price downturn hurts both rich and poor oil production countries. Pumping oil has become less and less profitable as prices have dropped below 40 dollars. Producers whose economies are especially dependent on oil, like Venezuela or Russia, suffer the most.
However, major wealthy exporters like Saudi Arabia and other Gulf countries are also under pressure. The International Monetary Fund (IMF) has warned that the Saudi currency reserves of 660 billion dollars could evaporate within five years.
"It is important that the government accelerate reforms that increase the employment of nationals in the private sector and diversify the economy away from oil," IMF chief Christine Lagarde has warned.
US shale oil producers: As Gulf countries have continued flooding the market with oil, they not only contributed to the price decline, but they also followed a strategy of pricing US shale oil out of the market.
This type of crude oil is extracted from rocks rather than wells, and production costs are higher than in Arab countries.
"Shale drillers in the US have slashed spending and cut the number of workers this year as prices have fallen," the Organization of the Petroleum Exporting Countries, which is dominated by Saudi Arabia, reported in December.
Oil companies: Multinational energy giants have recently seen profits drop and have shelved large-scale investment projects. Shell announced in September that it would stop exploratory drilling for oil in Alaska, a decision that cost the British-Dutch company 2 billion dollars.
Oil firms cut 20 per cent of their spending on developing and operating production sites this year, the International Energy Agency estimates.
The global climate: Some experts warn that cheap oil stands in the way of developing climate-friendly technologies, especially in the automotive and building sectors.
Demand for petrol-guzzling sport utility vehicles is on the rise in countries like the United States and Germany.
"Lower oil can lead to wasteful consumption and to the wrong assumption that oil will remain this cheap for all eternity," Kemfert said.