FACTBOX - French voters and the electoral system

(Reuters) - France will go to the polls on Sunday for the second round of the presidential election, choosing between right-winger Nicolas Sarkozy and his Socialist opponent Segolene Royal.

Here are some facts about voters and the electoral system:

* A candidate must win an absolute majority to get elected in the first round. When no candidate achieves this, the top two candidates face each other in the second round. Sarkozy secured a commanding lead in the opening round winning 31.8 percent of the vote, with Royal gaining 25.87 percent. The candidate who obtains the most votes in the second round is elected president.

* French women and men, aged 18 years and older, may vote. There are 44.5 million voters registered in France, a rise of 1.8 million or 4.2 percent compared with 2006. This is the largest rise in voter registration since 1981, according to the Interior Ministry.

* Polling stations are open across the country and in several French territories from 8 a.m. (7 a.m. British time) to 6 p.m. (5 p.m. British time) and until 8 p.m. (7 p.m. British time) in large cities.

* In the French Antilles, in Saint-Pierre-et-Miquelon, in Guyana, French Polynesia and in voting offices in continental America, voting in the second round takes place on May 5. The results are held until 1800 GMT (7 p.m. British time) the following day.

* Most voters will go into a closed booth to insert the ballot corresponding to their choice into an envelope, which is then dropped into the ballot box.

* This year, for the first time, over a million voters will be able to pick their candidate electronically. Computers will be installed at certain polling stations in hundreds of towns such as Amiens, Brest, Le Mans, Mulhouse and Reims.

* It will be the eighth time since the Fifth Republic began in 1958 that the French will directly elect the president who will serve a five-year term.