(a) Simple plurality system is an electoral system in which the candidate with the highest number of votes even though he may not have secured the majority of the votes is declared the winner of the election. It is also called the first-past-the-post system. It is common in the commonwealth countries and United, States of America.
(b) The repeated ballot is an electoral system in which voters vote continuously with intervals for discussions and negotiations until a winner emerges. A typical example is when a new pope is to be elected by a body of cardinals. The system is used in nominating the American presidential candidate at the party's convention/primary.
(c) The second ballot is an electoral system in which the two candidates who secured the highest number of votes are made to face the electorate at a later date. Voters who supported the less successful candidates are able to switch their support to either of the two leading candidates until a candidate secures the majority votes and wins. It is also known as " run-off.-election".
(d) The alternative vote is another electoral system designed to secure majority representation of the electorate. Under the system, voters are issued ballot papers in which they must indicate their preferences in order of importance, by marking 1, 2, 3, etc. The candidates with the least preference are repeatedly knocked out until a winner emerges.