Also called "second ballot" systems. In this system the candidate should achieve a specific percentage of votes to win in the election, it means that even you are the first candidate but if you cannot get that specific percentages votes you can't win. So if no one get a specific percentages, the election held after some days for the second election. Some name this system 50%+, because in some countries like Iran, for example in presidency election the winner candidate should get at least 50%+1 votes if they cannot succeed the election being held for the second time. This system has an important problem. If that specific percentage is very low (like Iran's parliament's election that the specific percentage is 20%) it isn't different by plurality system, even in our presidency election that the specific percentage is 50%+1 we have problem because if a person being winner by for example 50.5%, the about half of peoples agree with him/her and other people can be disagree with him/her.
Iran, France and many other countries use this system.
