What did the world most care about in 2015? Google News Lab looked at trillions -- that's right trillions -- of queries across Google search, Google News and YouTube to find out.
Here's a look at the top 30 news subjects the world wanted to know about this year. One hint -- the number one topic received nearly 900 million searches and far outpaced number two.
No. 30: 10 million searches +
Water on Mars apparently fascinated the world more than close-up photos of little Pluto. Perhaps it was because the discovery, announced in September, stirred the imagination regarding the potential for life beyond planet Earth and the desire to travel to the Red Planet.
Most popular questions: "How long does it take to get to Mars?" and "How far is Mars from Earth?"
Arizonans were the most interested in Mars among the residents of our 50 states.
By CBSNews.com Senior Photo Editor Radhika Chalasani
COP21 Paris Climate Conference
No. 29: 13 million searches +
World leaders and activists converged on France for the COP21 Paris Climate Conference from November to December, with the meetup resulting in the landmark Paris Agreement featuring a commitment to limit the temperature increase to less than 2 degrees Celsius.
Our oceans garnered the lion's share of our attention with coastal erosion, ocean acidification and rising sea levels being the most searched climate-related issues on Google.
Volkswagen emissions scandal
No. 28: 13 million searches +
When the Volkswagen emissions scandal made headlines, Americans and most of the world were primarily interested in knowing "Who owned Volkswagen?" while those in the UK and Germany were most concerned with which cars were affected.
The biggest search word was "emissions."
Pope Francis in America
No. 27: 14 million searches +
The media and the public is interested in most things Pope Francis does. His trip to America in September, the first official one, was hugely anticipated.
It seems that during his visit to Philadelphia, people had the most parochial of questions on their mind: "What roads will be closed for the Pope?"
Iran nuclear deal
No. 26: 20 million searches +
After much discussion and negotiation, President Obama announced an Iran nuclear deal on July 14, agreed to by leaders from the UK, Russia, France, China, Germany, China and Iran. The agreement capped more than a decade of on-again/off-again negotiations.
More people in Portland, Oregon were interested than anywhere else in the U.S. More people in Iran than anywhere else in the world took to the Internet to find out about the agreement.
Both "Iran nuclear deal" and "Iran Nuclear Program" were popular searches.
No. 25: 23 million searches +
Europe's biggest refugee crisis since World War II was on the minds of many, whether they lived in an affected country or not.
Interest was most intense when photos showing the lifeless body of 3-year-old Syrian refugee Aylan Kurdi, which washed up on a beach near Bodrum, Turkey. His name was part of the most searched terms or questions.
Cuba and the U.S. restore relations
No. 24: 27 million searches +
Interest in Cuba soared, especially in Florida, where many Cuban-Americans live. And the good news for the travel industry is that many people searched for travel to Cuba and Cuban destinations.
Cecil the Lion
No. 23: 32 million searches +
Animals are always close to our hearts. None more so in 2015 than the majestic Cecil, killed on July 1 in Zimbabwe by an American dentist.
Needless to say everyone on Google wanted to know who killed Cecil and the dentist, Walter Palmer, drew scorn from many parts of the world.
Greece debt crisis
No. 22: 35 million searches +
Greece's financial crisiscame to a head this summer and drew considerable interest when the country became the first developed nation to fail to make an IMF loan repayment. The country's exit from the Eurozone, after a "no" vote in a public referendum, was prevented by a deal with European creditors.
Naturally, the top questions globally were "What is happening in Greece?" and "What happens if Greece votes no?"
No. 21 : 42 million searches +
The FIFA scandal began in May with a raid on a luxury hotel in Zurich which led to the arrest of seven FIFA executives and the indictment of 14 current and former officials. Sixteen more officials were indicted in December.
Most searchers simply wanted to know what FIFA stood for and what the scandal was about. The most interest came from Germany, the UK, France and the U.S. The U.S. interest probably had a lot to do with America leading the charge by going after the officials.
No. 20: 73 million searches +
Who would've imagined that a simple striped dress would cause such a firestorm of debate and discussion. Even if you wanted to stay away from the whole thing, you couldn't.
In case you somehow missed the story, the frenzy started when a woman posted a photo of a dress she planned to wear to a wedding on Facebook. People couldn't decide if it was white and gold or black and blue. A simple thing, right? Not.
Sales of the dress soared 600 percent.
No. 19: 85 million searches +
The devastating 7.3 magnitude earthquake in Nepal on April 25 was one of those tragedies that the Internet helped galvanize assistance for the victims. With the death toll topping 8,000 and tens of thousands affected, the top question globally was "How can I help Nepal?"
Just shows that people can come together to help via the Internet.
Queen Elizabeth II
No. 18: 100 million searches +
While Britain's royal family is a consistent source of interest year after year, most of the spotlight usually is reserved for the younger generations. However, Queen Elizabeth II was high on the list in 2015.
And for good reason: The queen, who succeeded her father to the throne on Jun. 2, 1953, became the longest-reigning British monarch on Sept. 9. The top cities searching for news on the queen were not surprising in the former British empire -- Toronto, Brisbane, Sydney, Melbourne. But New York came in fifth, proving that Americans still love the royals.
One of the most interesting of the top questions asked: "Why does the Queen have two birthdays?"
Princess Charlotte is born
No. 17: 105 million searches +
The world was introduced to Britain's newest royal, Princess Charlotte, on May 2. The biggest related search was for mom, Catherine, Duchess of Cambridge (by a long shot) and dad, Prince William, Duke of Cambridge (not as much). Despite considering ourselves fans of the British royal family, the U.S. came in fourth in terms of interest by country. Australia, the UK and Canada had us beat.
Many royal fans spent time on the Internet searching baby names for the 8-pound, 3-ounce royal who is fourth in line to the throne, including Charlotte (the bookies' favorite), Alice and Elizabeth.
#Lovewins - Same-sex marriage
No. 16: 108 million searches +
According to Google, there was never more interest in same-sex marriage and the U.S. Supreme Court than in 2015 when the court extended marriage rights across the country to same-sex couples. The questions came from both sides of the political fence including "Where can I get a license?" to the phrase "against gay marriage" to "What does the Bible say about gay marriage?"
Both same-sex marriage and the Supreme Court had the highest amount of searches than at any time in Google's history.
Women's World Cup
No. 15: 113 million searches +
Team USA created huge excitement in 2015 as it made its way to a record third World Cup title. Interest peaked, of course, on July 5, when they defeated Japan for the championship.
The most-searched for name on the team? Goalkeeper Hope Solo.
And surprisingly enough, Costa Rica, Sweden and Paraguay generated the most searches. Go figure.
Top questions included "What year was women's soccer added to the Olympics?" and "How many women participate in football at grass roots level?"
Farewell to the brightest stars
No. 14: 123 million searches +
We care about the people we've lost and a significant number of us spent time searching for news about Leonard Nimoy, who portrayed the iconic character Spock in Star Trek, civil rights legend Julian Bond, Bess Meyerson, Beau Biden and former New York Gov. Mario Cuomo, among other well-known figures who died in 2015.
A new era in late night TV
No. 13: 141 million searches +
Late night TV underwent major changes with David Letterman and Jon Stewart signing off their respective shows. Stephen Colbert took over the reins from Letterman on "The Late Show" and a new face on the scene -- Trevor Noah -- replaced Stewart on the "Daily Show."
When your favorite TV show viewing gets disrupted it creates tons of questions and interest.
All the questions about new man on the spot, Trevor Noah, were to be expected, but even after all these years on TV, people still wanted to know "What happened to Colbert's ear?"
YouTube had a Letterman love fest including the more than22, 436,873 million global views for "Jimmy Kimmel Bids Farewell to David Letterman" and more than 1,972,291 million global views for the video "Jimmy Fallon Thanks David Letterman."
Royals win the World Series
No. 12: 144 million searches +
Sad to say that the World Series Champions, the Kansas City Royals, were not the most popular search in relation to the World Series. It seems their series rival, the Mets, had more fans.
It could've just been a question of rooting for the underdog, though, since the most popular question was "When was the last time the Mets won the World Series." It's been a while ... 1986.
No. 11: 155 million searches +
No surprise that "Star Wars" was a top search with more than 155 million generated with the release of first trailer for its newest installment. It is surprising, perhaps, that the most interest in "The Force Awakens" was from Australia, not the U.S. We have the Land from Down Under beat in population numbers, but not Internet interest apparently.
And Darth Vader was the most searched for "Star Wars" character when it came to overall searches on the topic.
Guns in America
No. 10: 160 million searches +
The San Bernardino shooting was just one in a long list of mass shooting in the U.S. in 2015, which naturally spurred high interest in gun control and the cities the shootings occurred in -- Charleston, Chattanooga, Roseburg, Colorado Springs and San Bernardino.
According to Google, searches for gun control actually topped those for gun shops, which normally is the dominant gun-related search across the U.S.
Black Lives Matter
No. 9: 189 million searches +
The Black Lives Matter movement continued its presence in the public discourse in 2015 with good reason. Americans became very familiar with the names of the victims of police-related deaths: Walter Scott, Freddie Gray, Sandra Bland and Laquan McDonald.
The largest number of searches were related to the Freddie Gray case.
No. 8: 216 million searches +
"The Fight of the Century" on May 2 may not have produced a knockout in the ring, but the bout between Floyd Mayweather Jr. and Manny Pacquiao for the world welterweight championship at the MGM Grand Garden Arena in Las Vegas was a hit on the hype scale and, therefore, sent the Internet swooning.
On Google, Mayweather, who came out on top in the bout, was the most popular.
Highlights on YouTube garnered more than 3 million views.
Rugby World Cup
No. 7 : 246 million searches +
From September to October, many eyes across the globe were on the Rugby World Cup. The New Zealand All Blacks defeated Australia 34-17 in London.
Cricket World Cup
No. 6 : 323 million searches +
While the U.S. may not have too many cricket fans, the rest of the world has plenty. It's hard to compete with India; with a population of more than 2 billion people, the country led the search bandwagon.
During the final, the top 10 questions on Google worldwide were all to do with the sport.
All that searching in India didn't help, though. Australia won the championship, defeating New Zealand.
No. 5: 338 million searches +
It's just the start of the very, very long American campaign 2016 to elect a new president. We were interested though.
No surprise that The Donald was the most searched for candidate on the web. Google and the polls were closely aligned there. The hot button topics for searches were immigration, same-sex marriage, education and taxes. Gun control came in fifth.
The most watched debate was the GOP one in August with 24 million viewers. It also produced the highest search of all the debates.
No. 4: 366 million searches +
Vanity Fair's cover of Caitlyn Jenner created an Internet sensation. People simply wanted to know "Who is Caitlyn Jenner?"
The cover also sparked record interest in the transgender community. Google said there were more searches on this topic than ever before. Interestingly, Jenner's biggest fans may be in Trinidad & Tobago, which recorded the highest number of searches of all countries around the world.
The video "Caitlyn Jenner is Finally 'Free' on Vanity Fair's Cover" was seen on You Tube more than 15 million times.
Jenner was also the third most searched for person in the world.
No. 3: 406 million searches +
We love the movies, so naturally the Oscars was the third most searched topic in 2015. "Birdman" may have walked away with the Best Picture honor, but "American Sniper" was the most popular film in terms of search.
No. 2: 439 million searches +
The English singer-songwriter Adele became the fastest trending musician on search with the release of her much-awaited third album, "25," garnering more than 439 million searches overall.
The most basic info people wanted to know: "When does Adele's album come out?"
The second most important question: "How old is Adele?" You can Google it.
"Hello" was the most trending video on YouTube with 766 million + views.
Paris under attack
No. 1: 897 million searches +
Terrorism in Paris took top billing. The Paris attacksmade the simple search "Paris" the most frequently searched term over the past year, more than twice as much as second place Adele.
The most natural questions: "What happened in Paris?" and "Who were the terrorists?"
The Nov. 13 attack that killed 130 people was the deadliest event on French soil since World War II.