In 2016, both the Republican and Democratic conventions will be held in late July before the Rio de Janeiro Summer Olympics, instead of after the Olympics as in 2008 and 2012. One reason why the Republican Party scheduled its convention in July was to help avoid a longer, drawn-out primary battle similar to what happened in 2012 that left the party fractured heading into the general election. The Democrats then followed suit, scheduling their convention the week after the Republicans’ convention, to provide a quicker response.

The purpose of every nominating convention, both Republican and Democratic, is to officially nominate the party’s candidate for president and vice president, and to adopt the party’s platform and rules.

Decades ago, power brokers, big-money donors, and thousands of delegates descended on a chosen city with the goal of picking and then nominating candidates for president and vice president. Since 1980, however, that purpose has changed: The conventions now are designed to sell, rather than select, the politicians who rank-and-file voters chose at the polls. They are made-for-television productions that build over four days toward a grand finale—the lengthy address that offers nominees an opportunity to introduce themselves to voters, rally the party faithful, and audition for the role of president.