- Each national party apportions a specific number of delegate votes to the various states and territories, based on state population and complex calculations of party strength and support in recent elections.

- The rules governing delegate allocation to candidates vary across parties, from state to state and are dependent on whether delegates are pledged or unpledged.  Click here for more information on the delegate allocation method.

- Candidates need a simple majority, or half the national delegate total plus one, in order to win their party's nomination.

Click here to learn more about how NBC News projects election winners.