South Carolina holds the first-in-the-South primary this coming Saturday. The primary, the third voting contest of the 2012 election season and the second to award delegates, is considered to be a make-or-break moment for the GOP candidates.

"Since 1980, no Republican has won the Presidential nomination without first winning South Carolina," Chad Connelly, chairman of the South Carolina GOP, told ABC News. "Our motto is, 'We Pick Presidents.'"

Twenty-five delegates are up for grabs in Saturday's contest. That number represents a 50% reduction of their original 50 delegates. The state was penalized for moving its primary date ahead of Feb. 1, a move made to preserve South Carolina's status as the first primary in the South after Florida jumped the line and moved its primary date to Jan. 31.

Delegates will be awarded as winner-take-all per district, meaning that the candidate who receives the most votes in any congressional district will be awarded the district's two delegates. The candidate receiving the highest percentage of the vote statewide will receive all 11 additional at-large delegates.

As with New Hampshire and Iowa, the number of delegates at stake is not the main reason for South Carolina's important role in the nominating process. It's the Palmetto state's history of flawless predictions. Ronald Reagan, George H.W. Bush, Bob Dole, George W. Bush and John McCain each claimed victory in South Carolina.

As of Jan. 1, 2012, South Carolina counted 2,722,344 registered voters - 79% of the voting eligible population of 3,434,551. In South Carolina, voters do not register by party, so any registered voter can participate in the Republican primary.

Polls open at 7 a.m. and close at 7 p.m. (EST). Voters across the state will cast their votes using machines called "direct recording electronic voting machines" or "DRE's." The South Carolina State Election Commission explains how the process works on their webpage.

Unlike in New Hampshire, the South Carolina ballot only counts nine Republican candidates, according to a sample ballot linked on the state election commission's website. Candidates who have dropped out of the race - Rick Perry, Michele Bachmann, Herman Cain, Jon Huntsman -are listed. Also, unlike in New Hampshire, the state will not hold a Democratic primary this coming Saturday.

Two key counties to watch out for in Saturday's primary are Greenville and Lexington. Located in the northwestern part of the state, Greenville is South Carolina's most populous county. The county has a history of favoring socially conservative candidates. George W. Bush dominated Greenville in 2000 with 58% of the vote, and Mike Huckabee carried it in 2008, with 29% of the vote to McCain's 26%. Romney received 17% of the votes in Greenville in 2008, and his performance in this cycle will be a telling mark of whether he's been able to successfully court the social conservative vote.

Greenville will also provide a window into the Gingrich and Santorum battle, particularly in light of Rick Perry's recent departure from the race. The former Pennsylvania senator and the former House Speaker are both vying for that spot as the anti-Romney candidate around whom the socially conservative base coalesces.

Lexington is not as populated as Greenville - it's the 6th most populous county in South Carolina - but it has been a bellweather county in recent years. In 2000 George W. Bush took the county with 59% of the vote. In 2008 McCain won with 33%.

Already four leading GOP candidates have dropped out of the race, and Saturday's contest may mark the end for more, depending on the results. Those candidates who remain in the race will pack their bags on Sunday and head to Florida. The sunshine state's primary is next up on the calendar, on Jan. 31.

ABC's Chris Good contributed to this report.