In general, primaries use secret ballots for voting. Caucuses are local gatherings of voters who vote at the end of the meeting for a particular candidate. The candidates then campaign across the country to explain their views and plans to voters. They may also participate in debates with candidates from other parties.
This plan was created by the German Gererals in the first world war to wage a succesful double war front. This plan firstly involved attacking France and Beljium.