The 2016 Presidential Election cycle gave rise to a new crop of candidates, and ideas that hadn't been included in the political discourse for some time. The term "Socialist" has become a sort of dirty word in American politics, one that the Right throws around to describe things they don't find appealing.
Bernie Sanders wore Socialism as a moniker, one that he used to unite a generation of people who are generally apathetic about politics. Utilizing populism and grassroots political movements, Sanders preached a message of equality and opportunity for all. His message reached people all across the country, people who are concerned with the decay of Social Security, or the failures of the Affordable Care Act. People gravitated towards him and his genuine care of the American people, something that fellow Democratic nominee Hillary Clinton failed to achieve.
On a personal note, Sanders has been a player in the political scene for decades. He successfully governed the largest city in his home state of Vermont, and he's served in the Senate for 10 years. He championed civil rights back in the 1960's, and still supports them today, even chanting out "Black Lives Matter" at one of his rallies.
Putting my personal opinions towards his policies to the side, I can safely say that Sen. Sanders is one of the most respectable and genuine Politicians in our current political system.