It's just about at end (apologies to states with primaries in Mid-May to June). This presidential campaign - which seemingly began immediately after President Obama was reelected in 2012 - has been steaming towards what seems to be the inevitable final showdown: Donald Trump -vs- Hillary Clinton.
Trump as the Republican candidate was not what anyone predicted, and not what anyone wanted. He's a joke, a showman, a used-car salesman, an intellectual fraud (which is saying a lot). Republic primary voters saw their clown car full of single-issue extremists and dullards, and decided to go all-in with the anti-politician candidate. Who better to be president than someone who doesn't know the first thing about how government actually works?
On the Democratic side, it started out interesting. Clinton was the assumed candidate, but the question was: who would run against her? Senator Bernie Sanders and Governor Martin O'Malley decided to give it a shot. O'Malley was definitely on the edges - he really had no national profile. Sanders was an odd choice as well - not a member of the Democratic party, he decided to run as one anyway. Most Dems welcomed him despite that as a foil to the perceived coronation of Clinton. It was certainly questionable how well he would be able to do as an "outsider" to the party (although very much an insider with regards to politics and the government). He has done exceedingly well.