A car drives past the U.S. diplomatic mission in Havana, Cuba, in 2013. (Desmond Boylan/Reuters)

Three months after taking office in 2009, President Obama brought up Cuba at the Summit of the Americas. "I know there is a longer journey that must be traveled to overcome decades of mistrust," he told the crowd, which did not include any representatives from Cuba, "but there are critical steps we can take toward a new day."

In the five years since, long-standing restrictions on travel and trade have been loosened and rhetoric has continued to focus on improving relations. This week, an American held by Cuba for five years was brought home, and the White House announced plans to open an embassy in Havana.

To call this a big change for U.S.-Cuba relations somehow feels like understatement, given those simmering decades of discontent and distrust, which have functioned as a museum-quality live exhibit of the Cold War for all the people born after it ended.

Here's the backstory to help you get up to speed.

In 1959, revolutionaries led by Fidel Castro overthrew the Batista government. Castro's relationship with the Soviet Union, among other factors, led President Dwight D. Eisenhower to cease diplomatic relations with Cuba in January 1961. The Embassy in Cuba had been legislated about 38 years earlier, and the United States recognized the independence of the country less than 60 years before — at the same time they began leasing land at Guantanamo Bay.

As President John F. Kennedy took office in late January 1961, plans were already in place to overthrow Castro. In April of that year came the failed Bay of Pigs invasion, in which more than 1,000 Cuban exiles, trained by the CIA, invaded the country and were quickly defeated by Castro's far larger army. The mission embarrassed the White House and cemented the bad feelings between the two nations. (Cuba heartily celebrated what they saw as the 50th anniversary of their defeat of American imperialism in 2011.)

A year later, a full economic embargo stopped nearly all trade and travel between the United States and Cuba. A U.S. plane photographed Soviet nuclear missile sites in Cuba in October 1962, which led to a naval quarantine of the island — an effort to stop further delivery of weapons — and a brief moment when some officials thought that nuclear war might actually happen, events otherwise known as the Cuban Missile Crisis. The 13 days of White House talks that resolved the crisis were inevitably memorialized in a Kevin Costner action movie, featuring one of his best attempts to capture an accent.

For the rest of the Cold War, restrictions and diplomatic attempts waxed and waned, but no serious changes in the two countries' formal relationship changed. In 1982, the State Department put Cuba on the list of state sponsors of terrorism.

During the 1992 presidential election, another reason for continuing the United States' policy toward Cuba was born — the promise of attracting conservative Cuban American voters who approved of the embargo. The New York Times published this telling paragraph in October 1992:

"I think this Administration has missed a big opportunity to put the hammer down on Fidel Castro and Cuba," Mr. Clinton told hundreds of cheering Cuban-Americans at a dinner that raised $125,000 for his campaign.

In March 1996, President Bill Clinton signed the Cuban Liberty and Democratic Solidarity Act, which was a reaction to an attack on two civilian planes that left four Americans dead. The law tightened the existing embargo. Pope John Paul II tried to push the White House toward easing the embargo, saying that the sanctions were "oppressive, unjust and ethically unacceptable."

In 1999, the Baltimore Orioles played an exhibition game in Havana. The Baltimore Sun wrote at the time: "Baseball could do for Cuban-American relations what Ping-Pong diplomacy did in paving the way for the Nixon administration's opening to China in the 1970s. But it is no sure thing."

At the end of the year, 5-year-old Elian Gonzalez was the only survivor on a raft coming from Cuba. A long legal battle between the child's relatives in Miami and his family in Cuba ended with the boy returning to Cuba. He told CNN in 2013 that the United States' "unjust embargo provokes an internal and critical economic situation in Cuba."

President George W. Bush continued many of the same policies as Bill Clinton. In a 2002 speech, he once again, like all presidents before him, affirmed the United States' desire to see more democracy in Cuba — as well as the federal government's belief that opening up trade would ruin all hope of that happening. "It's important for Americans to understand, without political reform, without economic reform," Bush said, "trade with Cuba will merely enrich Fidel Castro and his cronies."

Bush said similar things in 2007. "As long as the regime maintains its monopoly over the political and economic life of the Cuban people," he said, "the United States will keep the embargo in place." Raul Castro, who had taken over for his aging brother, published an essay called "Bush, Hunger and Death" soon after Bush's affirmation of existing foreign policy was announced. Castro wrote that Bush was "threatening humanity with World War III, this time with atomic weapons."

President Obama's administration has featured a slow thaw in the decades of tension with Cuba. In the spring of 2009, the White House and Congress made it possible for Americans to send remittances to Cuba, or visit family members there. The policy was very different from what the United States had been doing for decades, but Obama used the same rationale, saying that the move was made to promote democracy in the region.

In December 2009, American USAID contractor Alan Gross was arrested in Cuba and accused of being a U.S. spy. The Cuban government said they would only release Gross if the United States agreed to release five Cuban spies caught in Florida.

The push for stopping the embargo and renewing diplomatic relations continued. In October, the United Nations voted for the 23rd time to condemn the embargo. The United States and Israel have been the only states to vote against the measure in recent votes.

Former secretary of state Hillary Clinton wrote in her recently published book "Hard Choices":

Near the end of my tenure I recommended to President Obama that he take another look at our embargo. It wasn’t achieving its goals and it was holding back our broader agenda across Latin America. After twenty years of observing and dealing with the U.S.-Cuba relationship, I thought we should shift the onus onto the Castros to explain why they remained undemocratic and abusive.

She told Fusion in July that she'd like to visit Cuba some day. Meanwhile, newspaper travel sections are publishing stories on the legal possibilities of visiting Cuba and meeting a dairy farmer, and advising that you always bring extra toilet paper.

Raul Castro and Obama shook hands at Nelson Mandela's memorial service, which was quickly imbued with much meaning by all those who noticed. Many elected officials, especially Republicans, saw the shake as a mistake. "Why should you shake hands with someone who's keeping Americans in prison?" Arizona Republican Sen. John McCain told Public Radio International. "Neville Chamberlain shook hands with Hitler."

Cuban Americans in Florida, once a reliable Republican voting bloc, have increasingly voted for Democrats. Public support for renewing diplomatic relations with Cuba has grown over the past decade.

In an interview with the Miami Herald earlier in December, Bill Clinton said: “I think we would be well on our way to doing it [ending the blockade] if they released Alan Gross. It is really foolish to allow what is clearly a questionable incarceration to imperil the whole future of U.S.-Cuban relations, but that’s not my call to make."

On Wednesday, Obama announced that Cuba relations were finally about to change in a big way. “We can’t keep doing the same thing over five decades and expect a different result," he said during a televised address.

This includes rethinking the state's designation as a sponsor of terrorism and easing sanctions. Secretary of State John Kerry has previously alluded to allowing Cuba to attend the Summit of the Americas next year — for the first time. This year's summit will spend a large chunk of time discussing human rights and democracy, according to Kerry.

Republicans' reactions to the change in diplomatic relations with Cuba have not featured much rejoicing, ensuring that this will be a much-debated topic in the 114th Congress and 2016 presidential election. (Only Congress can formally normalize relations and approve the construction of an embassy.)

On Jan. 3, 1961, a mere 53 years ago, Eisenhower made a statement announcing the breaking off of diplomatic relations with Cuba.

"It is my hope and my conviction that in the not-too-distant future it will be possible for the historic friendship between us once again to find its reflection in normal relations of every sort," Eisenhower said.

Today, Obama took a big step toward doing just that.