Delegate cheat sheet: they hoot and holler and wear funny hats. But just who are these people?

The rules on delegates can make your head spin. Superdelegates can vote any way they choose. A candidate can win a state's popular vote but get fewer delegates. And although news organizations update their delegate tallies daily, it seems that no one has the same count. For clarity--and a guide that goes deeper than just defining terms--we offer the following crash course on the selection and role of delegates. Our instructors are James Thurber, an American University professor who has written extensively on the American electoral process, and Alicia Prevost, who helped oversee the delegate selection process for the Democratic National Committee in 2004.

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What Are the 2008 Delegate Selection Rules?

In the Republican and Democratic primaries and caucuses, there is only one prize: delegates. At the end of the summer, thousands of delegates elected to the Republican and Democratic conventions will gather to officially nominate each party's presidential candidate. Where do these delegates come from?

To determine how many delegates are allocated to each state, the parties use a formula that accounts for the state's population and its past support for the party's presidential nominee. For the 2008 conventions, there will be 2,380 Republican delegates and 4,049 Democratic delegates. Although Republican and Democratic delegates differ in many ways, each party has two basic types of delegates: pledged and unpledged. The Democrats have national rules governing all of these delegates; Republican rules differ state by state.

As we saw in the Super Tuesday contests, the rules matter. Focusing on winner-take-all states was important to John McCain's strategy; the 15 percent viability threshold prevented John Edwards from getting many delegates; and the proportional representation rule that Democrats have used universally since 1988 is keeping the race for that party's nomination running long after Super Tuesday. …