A little over a year after the US and Cuba revealed their historic deal to take major steps toward ending their 50-plus years of hostility, which they had negotiated in secret, President Obama is in Cuba — the first president to visit since 1928.

This is a huge moment for Cuba, for President Obama, and for the US-Cuba relationship. But you might reasonably be wondering why this is happening now. How did things get so bad between the US and Cuba in the first place, and why has that lasted for such a long time? What is actually changing now, and what does it mean for the two countries? What follows is a guide to your most basic questions about the US and Cuba.

(Note: this article, which initially published in December 2014, and has been updated to reflect Obama's trip.)

1) What is the US-Cuba deal?

The deal between the US and Cuba is three things.

First, it's an exchange of concessions: The US will roll back parts of its economic embargo on Cuba, Cuba will allow greater internet freedom, both countries released some prisoners, things like that. The terms of the deal are not, in themselves, revolutionary. The embargo is still in place, and so is the travel ban, meaning US tourism to Cuba is still restricted, though those restrictions have been falling away rapidly since the deal was first announced.

Second, it's the beginning of a sure-to-be-difficult fight between President Obama and anti-Cuba hardliners in Congress over whether Obama can change America's 50-year-old policy of official hostility toward Cuba. Obama can only do so much without Congress's help, and the politics of this issue are divisive, even if public opinion favors Obama's ambition to reopen relations.

Third, and most importantly, this deal, along with Obama's trip, is a way for the US and Cuba to announce that they are done being enemies. The official diplomatic term for this is "normalize relations," which basically means to become friends. That is the most important part of this story, and it is truly historic. The story of how the US and Cuba came to be such enemies, and stayed that way long after the Soviet Union collapsed and the Cold War ended, is a fascinating and complex one — and one that is widely misunderstood.

2) Why have the US and Cuba had such a hostile relationship for so long?

Officially, the reason is the Cold War, and it's the explanation you'll most commonly hear. There is much more to it than that, but here is the Cold War explanation:

Cuba became an ally of the Soviet Union shortly after Fidel Castro took power in a 1959 Marxist revolution; the US was not happy about having a Soviet military proxy 90 miles from Florida. Cuba was afraid that the US would try to violently overturn Castro's revolution, and the US did in fact attempt this several times in the early 1960s. Castro even invited the Soviet Union to put nuclear missiles in Cuba to deter American aggression, sparking the 1962 Cuban Missile Crisis when the US tried to block the Soviet ships carrying the warheads.

Those four years spent on the precipice of full-blown war settled into a sort of miniature Cold War between the US and Cuba, one that was a proxy for the larger US-Soviet Cold War and lasted right up until 2014.

The fact that the US-Cuba Cold War so outlasted the "real" Cold War, which ended in 1989, should be your first hint that there is much more going on here.

3) So the US-Cuba conflict isn't about the Cold War?

There are two other less-understood forces that have kept tensions going for so long. In some ways, the US-Cuba conflict actually goes back to before the Soviet Union even existed.

First, America's hostility toward Cuba has been driven, in large part, by domestic politics: Since 1980, when 125,000 Cuban exiles landed in Florida and changed electoral politics forever, the peculiarities of the American political system have made it important for presidents to oppose Castro if they want to get elected. (More on that below.)

Second, Cuba's hostility toward the US is less about the Cold War than you might think. Castro's anti-Americanism was couched in Communist rhetoric, but in many ways he was much more driven by anti-imperialism. He saw his revolution as part of a struggle against the US and its attempted domination of Cuba that was older than the Soviet Union or Communism.

In this Cuban view, the Cold War was just a chapter in the Cuban struggle of resistance against US imperialism, which is why the US-Cuba conflict outlasted the Cold War. It's also why Castro is such a hero to many Latin Americans, who have long seen Castro as the vanguard of resistance against an imperial US trying to meddle with or control their countries.

There is no question that, during the Cold War, the US did do a great deal of meddling in Latin America, supporting horrific right-wing dictators and militias, often against Soviet-backed left-wing dictators and militias (and sometimes against democratically elected leftists).

But Cuba was different: during the 1800s and early 1900s, many American politicians explicitly argued that the US should become a European-style imperial power, and Cuba was almost always where they said US imperialism should begin. Before the Civil War, legislators from southern states badly wanted to buy Cuba from Spain (it had been a Spanish colony for centuries) and annex it as a new slave state. In 1854, many of them issued an official manifesto trying to force President Franklin Pierce to make the offer, and to declare war on Spain if it said no.

The Civil War stopped that from happening. But, in 1898, Cuban political activists launched a war of independence against Spain — and the US joined the war on their side. The Spanish Empire was collapsing, sparking a debate within the US about the country's place in the world: Should America take Spain's place as an imperial power, seizing Spanish colonies — namely Cuba — for itself?

At first, anti-imperial Americans won the debate, passing the Teller Amendment, which promised to support Cuban independence and not annex Cuba. But pro-imperial Americans soon prevailed, passing something called the Platt Amendment.

The Platt Amendment said that if Spain lost the war, then Cuba would be nominally independent but dominated by the US, which would have the right to intervene militarily there whenever it wanted. That is how the US "leased" land from Cuba for its base at Guantanamo Bay, which it still owns. The US also annexed other Spanish colonies: Guam, Puerto Rico, and the Philippines. The US had become an imperial power.

In the following years, the US invaded and occupied Cuba twice — in 1906 and again in 1912 — to put down rebellions. It had mostly acquiesced its imperial powers over Cuba by the time that Fulgencio Batista took power in a coup in 1934, but the threat of American invasion still hung over the island. That history is largely forgotten in the US, but it is remembered in Cuba, and in much of Latin America, as if it happened yesterday — and the embargo is often seen as a direct continuation of that imperial past.

4) Why does the US embargo Cuba, anyway?

The US gradually rolled out the Cuba embargo between 1960 and 1962 (the embargo is a set of really powerful economic sanctions, forbidding almost all trade and travel between the two countries).

When Presidents Eisenhower and Kennedy set up the embargo in the early '60s, the official goal was to weaken Cuba's government to make it collapse outright, or to make Cubans so angry about their economic suffering that they take down the government in a popular uprising. It was the height of the Cold War, and a Marxist revolutionary, Fidel Castro, had just taken power in a 1959 rebellion against Cuba's pro-American dictator, Fulgencio Batista.

Castro nationalized all American businesses in Cuba — taking them over without compensating their owners — and declared ideological allegiance to the Soviet Union. The US immediately set about trying to topple Castro; the embargo was part of that, along with some really ill-conceived assassination plots and, in 1961, Kennedy's disastrous effort, known as the Bay of Pigs, to send CIA-trained, anti-Castro Cubans to invade the island.

The US eventually stopped trying to topple Castro by force, but it kept up the embargo as a means to weaken him until 1977. That's when President Jimmy Carter let part of the embargo lapse, in what looked like a possible first step toward dropping it. The embargo had failed, after all, to remove Castro. President Ronald Reagan reinstated the full embargo when he came into office in 1980, as part of his global effort against the Soviet Union and its allies.

Something else happened in 1980. Castro tried to relieve some internal political dissent by briefly allowing Cubans to leave the country. As a result, 125,000 migrated to the US, mostly to Florida. Many of these new Cuban-Americans, like the political exiles who had fled in the 1960s and '70s, hated Castro for what he had done to them, their families, and their country. And they voted on that.

By the time that the Cold War ended in 1989, Cuban-Americans had enough sway to make the embargo good politics. The fact that they are centered in Florida, an often-decisive swing state, meant that a presidential candidate's hopes and dreams could turn on whether or not his Cuba policy was sufficiently anti-Castro.

5) The US embargo failed to topple Castro. Why has the US kept it going anyway?

To understand that, it's not enough to just say that supporting the embargo will help presidential candidates win Florida. You have to go back to President Bill Clinton's first term, when a handful of decisive events set the embargo in stone for the next 20 years.

When Clinton came into office in 1993, lifting the embargo seemed obvious. The Cold War was over, and, in any case, the embargo had failed to remove Castro. But the Cuban-American community, which had grown prosperous since 1980, believed that Castro was moments from falling (Communist regimes across the world had collapsed in 1991 and 1992. and pressured Clinton against any show of lifting the embargo, for example, by generating fatal Congressional opposition to a Cuban-American State Department nominee who appeared to favor an opening. By 1996, Clinton had given up, and it became political conventional wisdom that the embargo was unopposeable.

But in those four crucial years from 1993 to 1996, neither the Cuban-American lobby or the Cuban-American vote, as important as they are, fully explain why the embargo continued to survive. Rather, the decisive event came in 1996.

That February, Castro's military shot down two private planes flown by members of a refugee organization that had reportedly previously dropped fliers over Cuba, and four Cuban-Americans were killed. The shootdown outraged Americans and moved popular and political opinion against opening relations. The following month, Congress overwhelmingly passed the Helms-Burton Act, which restricted the president's ability to end the embargo without Congressional approval and essentially promised to keep it in place, even if it didn't work.

Popular support for Helms-Burton was so strong that Clinton signed it, even though the law limited his own authority over Cuba policy. Pushing the bill was a politically brilliant move by Cuba hard-liners, including the Cuban-American community, but it could not have happened without Castro's decision to shoot down those two planes — and the moment of widespread American outrage against him that it had sparked.

In explaining his decision to sign the bill, Clinton later wrote in his memoir: "[It] was good election-year politics in Florida, but it undermined whatever chance I might have if I won a second term to lift the embargo in return for positive changes in Cuba."

Can we take a music break?

Great idea! But rather than listening to the Afro Cuban All-Stars or Buena Vista Social Club, which are excellent groups in Cuba's traditional folk-jazz tradition, let's try something more modern and more in touch with Cuba's special history as a melting pot of Caribbean culture — which includes the US. Here's Yerba Buena, a fantastic New York-based pan-Caribbean group that has very strong Cuban and American influences:

Soon, thanks to the US-Cuba deal, you will finally be able to legally kick back with a Cuban cigar and a glass of Cuban rum, both long banned, while you listen to this. It turns out that Cuban cigars aren't just popular because they're banned, they really are better — it's been confirmed by actual scientific studies.

6) Why is all this — the embargo, the century of hostility — changing now?

There are a few reasons. With the Cold War over, Cuba is no threat to the US, and the US, having given up its imperial ambitions in the 1930s and its anti-Castro plots in the 1960s, is no threat to Cuba. The events of 1993 to 1996 delayed the end of the embargo, but it was probably inevitable.

Also, within the US, popular opinion has turned sharply against the embargo. People just don't fear Cuba or Communism anymore, and they would like to go on vacation there. Even among Cuban-Americans in Florida, public opinion now supports, if very slightly, lifting the very embargo that community has spent decades lobbying to keep.

It's not that the political exiles changed their minds. Rather, there is a new generation of Cuban emigres to the US, who traveled here for economic reasons — to work and to send home money — rather than political reasons. This generation is focused less on hating Castro and more on helping their families. They would like to be able to travel back to Cuba more freely and send more money home from the US.

And then there's the fact that the embargo was always a dumb policy. It was not going to topple Castro, nor was it going to improve human rights in Cuba. The embargo is 1960s thinking in a 2010s world, and you can see that in the way that US policy toward Cuba is at tension with itself. The US wants to promote internet access in Cuba, for example, as a way to raise the standard of living, the flow of information, and public pressure for democratic change. But the US government's own embargo makes that really hard to do, which is why you have fiascos like "Cuban Twitter," in which the US secretly tried to create a Cuban social network to sow dissent.

Finally, Cuba needs to change — and its leaders know it. Since current Cuban leader Raul Castro took over from his ailing brother Fidel in 2008 (Fidel is still alive but appears to be suffering from possible dementia), he has been quietly seeking some sort of detente with the US like the one just announced.

Castro, just like anyone else, can look at nominally communist countries like China and Vietnam and see that they have transitioned to quasi-free-market economies successfully. And, for years, he has been reliant on donations from the oil-rich Venezuelan government to keep the Cuban economy afloat — something that appears more unreliable all the time as Venezuela's economy and political system teeter on the end of collapse.

7) I hear that Fidel Castro is a monster who did lots of terrible things. Is that true?

Oh yes. Dropping the embargo is the right thing to do, and the US has a long history of doing bad things in Latin America and Cuba, but none of that should in the least bit forgive the Castro regime's atrocious record on human rights.

Cuba, to be clear, is a dictatorship. Cubans have very few political rights or freedoms. The country has lost restricted free speech, punished political dissent severely, and for many years systemically persecuted and imprisoned certain groups, particularly gays and lesbians, often in terrible conditions.

According to Freedom House, Cuba has the most restrictive press censorship in the Western Hemisphere and is the only country rated "not free" in the Americas. All official media is owned by the state and controlled by the government. Dissident bloggers are regularly arrested. According to Amnesty International, protestors are regularly arrested and detained without trial. The Foundation for Human Rights in Cuba says there were over 6,000 arbitrary detentions of human rights activists in 2013.

Once in jail, detainees face harsh conditions. "Prisoners often slept on concrete bunks without a mattress," according to the State Department's human rights report on Cuba, "with some reports of more than one person sharing a narrow bunk. Where available, mattresses were thin and often infested with vermin and insects."

8) But this deal means that Cuba is going to become a freedom-loving capitalist democracy now, right?

That's the idea: that opening up Cuba's economy to outside investment and tourism will help liberalize the country more broadly, as the flow of ideas, money, and people helps along preexisting Cuban desires for greater freedoms and rights. That's also why one of the American conditions for the recent deal is that Cuba will allow wider internet access, thus encouraging the growth of a grassroots political culture.

But it's tough to say whether this will work. While the deal will likely liberalize Cuba's economy, there's nothing in it that actually requires Cuba to become one iota less authoritarian, and it's not clear that economic openness will lead to democracy. The record of communist countries that have opened up is mixed. When the US normalized relations with the Soviet Union, that opening helped along internal political reforms that turned the country into a free-market democracy, however briefly.

China and Vietnam, on the other hand, liberalized their political systems a tiny bit when they opened their economies, but have so far largely maintained single-party authoritarian rule. Cuba's ruling political class, presumably, would rather be like China than like Russia.

It may ultimately come down to what the aging Castros, and the wider ruling class that supports them, want to do. Dictatorships that have wanted to liberalize, either because they thought it was the right thing to do or under internal pressure, have tended to be successful. Dictatorships that want to hang on at any cost are often successful, or plunge their countries into chaos trying.

One thing is for sure, though: maintaining the embargo and the official policy of US hostility was not going to bring democracy and freedom to Cuba.

9) I skipped to the bottom. What's going to happen next?

The immediate ramifications are going to be a touch more trade and travel with Cuba (though most US tourism is still illegal), the opening of a US embassy in Havana (above which the US flag now flies), and the start of what will surely be a difficult but interesting period of renewing US-Cuba relations.

There will also be a political fight in the US, and especially Congress, over whether to end the embargo outright — something that only Congress can do. That fight will coincide with the presidential election. While supporting the embargo is GOP orthodoxy, and many Republican leaders oppose Obama's policy, national popular opinion has shifted in favor of ending the embargo.

How the Cuba policy fight plays out within the GOP over the next year, then, could help shape how American politics, and American policy, change toward Cuba.

But the largest effect, and the most important, will almost certainly be within Cuba itself. The Castro government will have to adjust, if slowly, to a new world and to ending the enmity with the US that has defined Cuban politics for half a century. What that means for the future of Cuba and its people will surely be one of Latin America's most fascinating stories in the coming years and decades.