The United States has just become the 21st nation to legalize same-sex marriage.

It is official! By a 5-4 vote, the Supreme Court has just issued a sweeping ruling legalizing same-sex marriage across the country. Justice Anthony Kennedy issued the court's opinion. Here are some highlights:

"The ancient origins of marriage confirm its centrality, but it has not stood in isolation from developments in law and society. The history of marriage is one of both continuity and change. That institution—even as confined to opposite-sex relations—has evolved over time."

"These new insights have strengthened, not weakened, the institution of marriage. Indeed, changed understandings of marriage are characteristic of a Nation where new dimensions of freedom become apparent to new generations, often through perspectives that begin in pleas or protests and then are considered in the political sphere and the judicial process." "The nature of injustice is that we may not always see it in our own times. The generations that wrote and ratified the Bill of Rights and the Fourteenth Amendment did not presume to know the extent of freedom in all of its dimensions, and so they entrusted to future generations a charter protecting the right of all persons to enjoy liberty as we learn its meaning. When new insight reveals discord between the Constitution’s central protections and a received legal stricture, a claim to liberty must be addressed." "These considerations lead to the conclusion that the right to marry is a fundamental right inherent in the liberty of the person, and under the Due Process and Equal Protection Clauses of the Fourteenth Amendment couples of the same-sex may not be deprived of that right and that liberty." "No union is more profound than marriage, for it embodies the highest ideals of love, fidelity, devotion, sacrifice, and family. In forming a marital union, two people become something greater than once they were. As some of the petitioners in these cases demonstrate, marriage embodies a love that may endure even past death. It would misunderstand these men and women to say they disrespect the idea of marriage. Their plea is that they do respect it, respect it so deeply that they seek to find its fulfillment for themselves. Their hope is not to be condemned to live in loneliness, excluded from one of civilization’s oldest institutions. They ask for equal dignity in the eyes of the law. The Constitution grants them that right."

Interestingly, all four dissenting Justices wrote opinions.

Among other things, Chief Justice John Roberts said:

"Supporters of same-sex marriage have achieved considerable success persuading their fellow citizens—through the democratic process—to adopt their view. That ends today. Five lawyers have closed the debate and enacted their own vision of marriage as a matter of constitutional law. Stealing this issue from the people will for many cast a cloud over same-sex marriage, making a dramatic social change that much more difficult to accept." "Understand well what this dissent is about: It is not about whether, in my judgment, the institution of marriage should be changed to include same-sex couples. It is instead about whether, in our democratic republic, that decision should rest with the people acting through their elected representatives, or with five lawyers who happen to hold commissions authorizing them to resolve legal disputes according to law. The Constitution leaves no doubt about the answer."

Justice Antonin Scalia's dissent contained his characterstic flair:

"So it is not of special importance to me what the law says about marriage. It is of overwhelming importance, however, who it is that rules me. Today’s decree says that my Ruler, and the Ruler of 320 million Americans coast-to-coast, is a majority of the nine lawyers on the Supreme Court. The opinion in these cases is the furthest extension in fact— and the furthest extension one can even imagine—of the Court’s claimed power to create 'liberties' that the Constitution and its Amendments neglect to mention. This practice of constitutional revision by an unelected committee of nine, always accompanied (as it is today) by extravagant praise of liberty, robs the People of the most important liberty they asserted in the Declaration of Independence and won in the Revolution of 1776: the freedom to govern themselves." "The opinion is couched in a style that is as pretentious as its content is egotistic. It is one thing for separate concurring or dissenting opinions to contain extravagances, even silly extravagances, of thought and expression; it is something else for the official opinion of the Court to do so." "Hubris is sometimes defined as o’erweening pride; and pride, we know, goeth before a fall. The Judiciary is the 'least dangerous' of the federal branches because it has “neither Force nor Will, but merely judgment; and must ultimately depend upon the aid of the executive arm” and the States, 'even for the efficacy of its judgments.'"

Justice Samuel Alito added:

"Until the federal courts intervened, the American people were engaged in a debate about whether their States should recognize same-sex marriage. The question in these cases, however, is not what States should do about same-sex marriage but whether the Constitution answers that question for them. It does not. The Constitution leaves that question to be decided by the people of each State. " "Today’s decision usurps the constitutional right of the people to decide whether to keep or alter the traditional understanding of marriage. The decision will also have other important consequences."

And Justice Clarence Thomas rounded off the dissenting opinions:

"The Court’s decision today is at odds not only with the Constitution, but with the principles upon which our Nation was built. Since well before 1787, liberty has been understood as freedom from government action, not entitlement to government benefits. The Framers created our Constitution to preserve that understanding of liberty. Yet the majority invokes our Constitution in the name of a 'liberty' that the Framers would not have recognized, to the detriment of the liberty they sought to protect. Along the way, it rejects the idea—captured in our Declaration of Independence—that human dignity is innate and suggests instead that it comes from the Government. This distortion of our Constitution not only ignores the text, it inverts the relationship between the individual and the state in our Republic. I cannot agree with it."

Immediately following the ruling, social media was flooded with messages of celebration, support, and love.

Today is a big step in our march toward equality. Gay and lesbian couples now have the right to marry, just like anyone else. #LoveWins — President Obama (@POTUS) June 26, 2015

Our new favorite map. RT if you live in a state where marriage equality is law. pic.twitter.com/7GlCwCJHyg — Hillary Clinton (@HillaryClinton) June 26, 2015

Huge day for America.. Happy to see the news. All the love — Harry Styles. (@Harry_Styles) June 26, 2015

Shortly after the announcement, President Barack Obama called Jim Obergefell, the lead plaintiff in the winning case.

A little over an hour after the the verdict, President Barack Obama held an emotional press conference celebrating the historic ruling.

Later, the White House published an open letter from Jim Obergefell, one of the plaintiffs in the victorious case. The letter is a touching tribute to his late husband and the importance of this day:

"My husband John died 20 months ago, so we’re unable to celebrate together the Supreme Court’s decision on the case that bears my name, Obergefell v. Hodges." "John and I started our fight for a simple reason: We wanted the State of Ohio to recognize our lawful Maryland marriage on John’s impending death certificate. We wanted respect and dignity for our 20-year relationship, and as he lay dying of ALS, John had the right to know his last official record as a person would be accurate. We wanted to live up to the promises we made to love, honor, and protect each other as a committed and lawfully married couple." "I can finally relax knowing that Ohio can never erase our marriage from John’s death certificate, and my husband can now truly rest in peace. Marriage is about promises and commitments made legal and binding under the law, and those laws must apply equally to each and every American."

While marriages are still on hold in Louisiana, they have already begun in Georgia, Ohio, Tennessee, Kentucky, South Dakota, Michigan, and certain parts of Alabama and Texas.

VIDEO: More on 1st same-sex couple to marry here, comments from judge who rejected state ban: http://t.co/4gFYoU8wrP pic.twitter.com/mMnsKQf2Ly — Gavin Lesnick (@glesnick) June 26, 2015

BREAKING: South Dakota county issues same-sex marriage license in wake of Supreme Court ruling. — The Associated Press (@AP) June 26, 2015

This couple in their 80s just arrived to the Records Bldg in #Dallas. They're here 2 get a marriage license. #Scotus pic.twitter.com/6syxFucght — Stella M. Chávez (@stellamchavez) June 26, 2015

BREAKING: Kentucky governor instructs county clerks to issues marriage licenses to same sex couples. — The Associated Press (@AP) June 26, 2015

First Franklin Co same sex couple, Jimmie and Mindy, receive their marriage license. @wosunews pic.twitter.com/itbNLFnXgT — Mandie Trimble (@mandiewosu) June 26, 2015

Family and friends wedge themselves between media for Nashville's second same sex marriage. pic.twitter.com/6OMaqXTd0r — Adam Tamburin (@tamburintweets) June 26, 2015

The state of Georgia is subject to the laws of the United States, and we will follow them. — Governor Nathan Deal (@GovernorDeal) June 26, 2015

Facebook released a special rainbow flag fliter for Pride. Someone tried to troll Arnold Schwarzenegger, and he came back in true Terminator fashion:

Around the country and across the globe, iconic landmarks showed their support for marriage equality and pride:

If you liked our avatar, you'll love the view from Pennsylvania Avenue tonight. http://t.co/uarb5ry1xo #LoveWins — The White House (@WhiteHouse) June 26, 2015

The Niagra Falls this evening. pic.twitter.com/3CfLG5cPSB — Tyler S. Bugg (@tsbugg) June 27, 2015

PIC: Little Rock lit in rainbow colors as rain falls #ARNews pic.twitter.com/y25H0NqBDs — Austin Kellerman (@AustinKellerman) June 27, 2015

More updates to follow...