Many of my readers have never experienced a brokered convention. If you weren't born yet, or weren't active in politics, before 1960, you may not have ever experienced one. A brokered convention is one that a clear cut winner does not emerge prior to the start of the convention. That leaves it up to the delegate to change, stay with or punt, usually after the third ballot, individual delegates are freed from the obligation to vote for the candidate who's slate they represent. That varies from state to state, as the states control the rules for their delegations.
Prior to 1960, most states didn't have primaries. Delegates were chosen by the parties leaders in that state, or by caucus. That and back to the birth of the country almost, was the method of selecting delegates. Some real abuses occurred, of course, with Tammany Hall, machines such as the Daley one in Chicago and on and on. The single one event that changed the system forever, was the advent of Television. Instead of back room or as they used to say,"smoke filled rooms," party bosses and their disciples making the rules. With the advent of TV, sound bites and direct campaigning to the public gradually eliminated most of the machine antics of yesterday. Primaries were adopted in most states, which again, eliminated the bosses and went directly to the voters.
A brokered convention isn't all bad. It's great entertainment. I remember the battle between Senator Estes Kefaufer and Senator Adlai Stevenson in a long ago Democratic convention,1952 and again in 1956 The favorite was Kefaufer, but Stevenson had better floor managers and on about the umpteenth ballot, was nominated. This is great entertainment, folks.Whether you are a Republican or Democrat, if you are a political junkie, brokered conventions are more fun than sex, and they last longer.