In a landmark decision, the Supreme Court ruled 5-4 in favor of same-sex marriage,  making it legal nationwide. Justice Anthony Kennedy, Justices Ruth Bader Ginsburg, Elena Kagan, Sonia Sotomayor and Stephen Breyer made up the majority, while Chief Justice John Roberts, Justice Antonin Scalia, Justice Thomas and Justice Alito dissented.

1. The decision: The Supreme Court ruled that the Fourteenth Amendment requires a state to license a marriage between two people of the same sex. The court also ruled that the law requires states to recognize a marriage between two people of the same sex when a marriage was lawfully licensed and performed out of state.

2. The majority opinion: According to the ruling, The majority concluded that same-sex marriage is a fundamental right on "four principles and traditions": (1) right to person choice in marriage is "inherent in the concept of individual autonomy"; (2) "two-person union unlike any other in its importance to the committed individuals"; (3) marriage safeguards children and families; (4) marriage is a keystone to our social order.  

The majority in their concluding paragraph of the decision stated:

"No union is more profound than marriage, for it embodies the highest ideals of love, fidelity, devotion, sacrifice, and family. ... [The challengers] ask for equal dignity in the eyes of the law. The Constitution grants them that right."

>>Read the Supreme Court opinion (PDF)

3. The dissent: In his dissent, Chief Justice John Robert wrote, "If you are among the many Americans--of whatever sexual orientation--who favor expanding same-sex marriage, by all means celebrate today's decision. Celebrate the achievement of a desired goal. Celebrate the opportunity for a new expression of commitment to a partner. Celebrate the availability of new benefits. But do not Celebrate the Constitution. It had nothing to do with it."

Justice Antonin Scalia began his dissent  by saying the decision is a “threat to American democracy."

4. What it means: Same-sex marriage is now legal nationwide. States will be required to recognize same-sex marriages from other states. It is unclear if all 50 states are currently equipped to issue same-sex marriage licenses immediately.

5. Reaction: A huge crowd cheered outside of the Supreme Court when the decision was read. Social media reaction was also swift and overwhelmingly positive. #LoveWins and #LoveisLove are trending on Twitter.

>>Social media reaction to same-sex marriage ruling

>>Photos: See reaction from across the nation