What determines how a candidate is chosen when no candidate wins a majority of votes in a primary election?

The primary elections are for delegates to the National nomination convention. Not all states have them and the way in which they select delegates varies. Sometimes the delegation is divided in proportion to the vote, sometimes the one with the most votes get all of the delegates. Sometimes the primaries are only advisory information for the delegates. If no candidate has a majority of the bound and committed delegates by convention time, delegates are all free after the first ballot to vote as they choose. Ballots are taken and deals are made and delegates switch votes until finally one candidate has a majority.