A caucus is a local gathering where voters openly decide which candidate to support. The caucus format favors candidates who have a dedicated and organized following because a small band of devoted volunteers can exert an out sized influence in the open setting of a caucus.There is no secret ballot concept or privacy in the process, This would have been the vision our Founding Fathers had for American politics.
Although it may seem insulated from the originals ideas of the founding fathers, one must take into account the huge population growth of the United States since then. A Caucus is a perfectly valid form of representative democracy and one of the best options among the other alternatives for determining a Presidential frontrunner.
I think that the idea of a caucus just seems so old fashioned, that I imagine this is exactly how it was done back when our nation was founded. People make it known which candidate they are supporting, and with a show of hands and simply counting of people, a candidate is chosen. I think the highly public lack of privacy makes a caucus very different from a primary, and is probably how our Founding Fathers thought of voting.
The Founding Fathers had an idea when they built our country. They wanted Democracy, they wanted the people to be able to choose their own leader. The Primary is a better way of doing this. With a Primary the voters directly choose whom they want to vote for in the election, the indirect voting on the Caucus does not.