With the new year upon us, several of the BBC's experts have been asked to give their predictions on which stories to follow in 2015.
Security, refugees and the battle against Islamic groups
Lyse Doucet, chief international correspondent
2015 will be another year of global consequence in the Middle East and just beyond.
The year ended with major security challenges in both Pakistan and Afghanistan. This situation will be further aggravated in 2015. Better relations between Pakistan, India and Afghanistan will be essential but difficult.
2015 will be a critical year in the battle against Islamist groups on many fronts.
The US will strive to limit its military engagement but won't be able to pull away despite President Obama's best laid plans to do so.
In Iraq, the US will strive to strengthen Iraqi forces to take back iconic cities seized by the Islamic State group. Iraq will remain fragmented, as will Syria, where a deadly stalemate will continue.
The UN predicts continued hardship for refugees, such as this 4-year-old Afghan girl in Islamabad, in 2015
Financial pressures stemming from a sustained slump in oil prices will not cause key players to abandon their allies but will increase pressure to find a way out.
Oil producers Russia and Iran - President Bashar al-Assad's key backers - will weigh new political approaches including the UN plan for a local "freeze" in Aleppo. The West, Arab states and Turkey will continue to back different forces, impeding any united opposition front. Assad's own forces are stretched, and strained.
2015 is a pivotal year on other fronts. There are reasons to believe a deal will be reached on Iran's nuclear programme. US Secretary of State John Kerry will try to revive Israeli-Palestinian talks after Israel's elections but there are too many tensions in the mix to make real progress possible.
This will be another year of global hand wringing over the inability of world powers to resolve many major crises. And, all the while, the armies of the desperate will continue to swell with ever more people forced to become refugees or migrants risking their lives at sea.
Bridget Kendall, diplomatic correspondent
Western diplomats face two major challenges as 2015 dawns: how to contain contagion from Syria's collapse; and how to tackle a resurgent Russia.
On the first, in theory a nuclear deal with Iran could unveil a new paradigm in the Middle East, transforming Tehran from pariah into partner.
Many hope a long-term deal with Iran over its nuclear programme can be reached in 2015
The West and Iran already share a common enemy - the IS jihadists currently dismembering Syria and Iraq. Both sides desire a deal, the West to avoid a nuclear-armed Iran, President Rouhani to get sanctions lifted.
But the window for compromise is closing: sceptical Republicans now controlling Capitol Hill encumber President Obama and Tehran conservatives would rather block than back a deal ahead of parliamentary elections.
Then there is what to do about Syria's President Bashar al-Assad, Iran's key ally, but unacceptable as part of any compromise in many Western capitals.
So the most likely outcome is continued mayhem, contained somewhat by air strikes, with the hydra-headed problem left for the next American president, while Iran seeks other ways to breach the stranglehold of sanctions.
Likewise a deal with Russia over Ukraine may appear preferable to an escalating conflict. And you might think Russia's economic worries would make Mr Putin more pliant.
The Ukraine crisis has put Russia's ties with the West are at their lowest ebb since the Cold War
But loss of trust on all sides makes a breakthrough unlikely. Kiev and Western powers now view Moscow with the utmost suspicion. And President Putin welcomes reduced contacts with the West as an opportunity for Russia to become more self-reliant.
A de facto border already divides Ukraine proper from the self-styled eastern enclaves next to Russia. Expect a broader barrier to take shape over 2015, reminiscent of the Iron Curtain, but virtual not actual.
The West will blame Russia. And Mr Putin will blame the West, while encouraging Russians to turn inwards, away from the malign influence of foreigners.
The pressures of globalisation will mean fragmentation of our more integrated world.
The US will boom, Europe will stagnate or worsen, and China is the wild card. Inequality will rise, and no-one will know what to do about it. That will feed the feeling that politics doesn't work.
The debate about Western intervention will heat up
The conflicts of 2014 will deepen and probably worsen and new ones will erupt - both that, and the US election around the corner in 2016 will intensify the debate about Western intervention.
The next US president will have to work out if there is a middle way between Bush's adventurism and Obama quietism. Other countries may start to reflect that, prompting a better, less dangerous world.
Europe will have to decide if it wants to stick at its current borders - if Ukraine and Turkey will never join, the EU will have changed course. Like many other political projects the EU may start to deflate if is stops expanding.
The internet will become a philosophical battleground as it increasingly freaks out the gerontocracy, unnerved by a lack of control, faced by a younger generation who largely think the good of the medium outweighs the bad of any messages it may contain.
China: Political purge, high growth and internet governance
Carrie Gracie, China editor
China's rulers have much to grapple with
2015 will be dominated by the ongoing anti-corruption campaign, a drive to make the Communist Party fit for purpose, clearing President Xi's remaining political enemies from the field and scaring the bureaucratic machine out of its habits of self-serving greed and cynicism.
The "new normal" economics slogan is about weaning China off a high growth model after more then 30 years. Reform is more urgent than ever, but putting it off is making it ever harder.
Hong Kong's Legislative Council will or won't approve rules on electing the territory's next leader. Whichever way, the divisions exposed by the Occupy movement will be hard to bridge.
Clean air, soil and water go on being big challenges for the long term. Expect some progress on emissions pledges made during the Xi-Obama summit in November 2014, especially as we get closer to the big Paris conference in autumn 2015.
Prince William's visit at the beginning of March will be a moment to push public education on protecting elephants, rhino and species at home. Conservation is one of the few areas where NGOs are permitted to operate in China.
With China's tech market impossible to ignore, expect to see Mark Zuckerberg back in Beijing, working his Mandarin and making compromises for Facebook access. Watch China use its new leverage with the Californian tech companies to push harder for a stake in global internet governance.
Lots happening in terms of defence, for example China's nuclear armed submarines will become operational and its big defence companies will go looking for global arms sales.
Another year of energetic diplomacy by President Xi and Prime Minister Li to push China's geopolitics and commerce, particularly the Silk Road Economic Belt to control China's backyard: energy, transport and security dominance in Central Asia.
A tougher line from a Republican-controlled Congress may make US-China engagement bumpier than ever in 2015, while the US electoral cycle weakens President Obama just as President Xi cements his authority for year three of ten.
Chinese companies are closing in on their Western competitors
Globally significant is the business power shift from west to east. Chinese companies and banks are all expanding rapidly westward, with many of these businesses not simply aping Western companies but beating them.
Alibaba (online commerce) is now closing in on US behemoth Walmart as the most valuable retailer in the world. 2015 could see it become one of the top ten most valuable businesses in the world.
China's move to significant global business player has been rapid, with it now the second largest foreign investor in the US behind Canada. It raises significant questions about the use of soft, economic and business power and how that plays into China's political influence across the globe.
The West needs money. China, a nation of savers with a $260bn trade surplus with the rest of the world in 2013, has it.
In 2015, the West will face many of the challenges experienced by African nations which have seen major levels of investment from China, often to service the latter's growing demand for food.
This raises challenges for Western businesses at just the time when the political discussion in many Western nations is more about de-globalisation and cutting businesses "down to size".
That's the anti-markets trend which has been strong in the West since the financial crisis, and will still be very visible throughout 2015.
Watch for significant developments in artificial intelligence and computers that think, fresh troubles in the eurozone and a major breakthrough in the hunt for an Ebola vaccine led by GlaxoSmithKline and Johnson & Johnson.
There will be continuing good economic news from the US (still the world's global powerhouse), support for global growth from the commodities price squeeze and, in general, a more optimistic economic and business mood at the end of the year compared to the beginning.
BBC.com