How the Academy Awards voting process works in 7 steps

— -- On Sunday night, PricewaterhouseCoopers, the accounting firm that handles Oscars voting, was thrust into the spotlight after the wrong name was read as the best picture winner at the Academy Awards.

Shortly afterward, PwC announced that the envelope given to presenters Warren Beatty and Faye Dunaway was incorrect, which led to the embarrassing blunder.

Though Dunaway announced that "La La Land" won the night's biggest honor, the statuette actually went to "Moonlight."

"We sincerely apologize to 'Moonlight,' 'La La Land,' Warren Beatty, Faye Dunaway, and Oscar viewers for the error that was made during the award announcement for best picture," according to a statement from PWC. "The presenters had mistakenly been given the wrong category envelope and when discovered, was immediately corrected. We are currently investigating how this could have happened and deeply regret that this occurred. We appreciate the grace with which the nominees, the Academy, ABC and [host] Jimmy Kimmel handled the situation."

For the past 83 years, PricewaterhouseCoopers has been responsible for tallying the votes. Like years before, partners Martha Ruiz and Brian Cullinan headed up the operation.

The two opened up to ABC News in 2016 about how the process works, which could give some insight into what went wrong Sunday.

1. Voting started early: After the nominations are announced, ballots are sent out to members of the Academy, each of whom decided ahead of time whether to vote electronically or with a paper ballot. Immediately afterward, according to Ruiz, a small group of PricewaterhouseCoopers employees counts each vote by hand at a secret location.

2. The voting process is an organized one: Though electronic voting was introduced five years ago, many members still choose to use paper ballots.

"We bring those to postal service and drop them off. They then go to the individual voters who complete the ballots, put them in an envelope that’s indicated with security codes and those come back to us," Cullinan said.

"We then have those in an undisclosed location. We don’t tell people where the voting takes place or where the tabulation takes place. And we have a team that helps us go through this, but each of our team members are only doing a portion of the total counting and myself and my fellow partner Martha are the only two who really know the winners."

3. There's protection from counterfeit ballots: PricewaterhouseCoopers makes sure that each ballot returned to them is legitimate by matching the code on it to the corresponding voting member. And while Cullinan said at the time that he'd never seen a fake ballot mailed in, he assured ABC News that it would be caught very quickly and wouldn't be counted.

4. Counting the votes takes days: For days before 2016's show, Cullinan and Ruiz holed up with their team counting ballots -- and that process continued for the rest of the week.

"We have a safe. We have multiple rooms with security and biometric locks and all kinds of things. Alarms that if doors are open for too long the LAPD shows up. A lot of those security measures that we have in place just to make sure that’s its always safe," Cullinan said. Ruiz added that once the ballots are counted, they're filed away for a few years and then shredded.