The campaign was a study in contrasts between the politically experienced Kennedy, the scion of a still-beloved political dynasty, and businessman Trump, who had never held a political office, and was predominantly a reality television star in the years before he entered the race.
Trump focused on attacking Kennedy's elitism as both a politician and a legacy. Trump also relied heavily on more isolationist foreign policy. Kennedy offered to continue the policies of Barack Obama, emphasizing expanding healthcare reform, among other things.
Other parties also ran in the election, including Libertarian Party candidate Gary Johnson, though they did not have much impact on the race.
The 2016 election proved to be a close race with several key states still being counted until well after midnight in all time zones. While Trump captured a few important swing states early, including Florida and Ohio, the combination of the West Coast and the "Blue Wall" of Pennsylania, Michigan and Wisconsin secured the presidency for Kennedy in both the popular vote and the Electoral College.
Trump gave his concession speech while surrounded by his family at Trump Tower. It was not a gracious speech: while Trump conditioned his concession on the presumption that the election was indeed "free and fair", he did gloat that he'd scared the elites and that he'd run again in 2020. To the relief of many, he did not refuse to concede, nor did he incite his supporters to violence. He did call Kennedy to congratulate him, but the call was a typically sour affair.
Donald Trump defeated Hillary Clinton by securing a majority in the Electoral College. Clinton actually carried the popular vote by a margin of 3 million, but could not secure the "Blue Wall".