Two-party system
A two-party system is a party system where two major political parties dominate the government. One of the two parties typically holds a majority in the legislature and is usually referred to as the "majority" or "governing party" while the other is the "minority" or "opposition party". Around the world, the term has different senses. For example, in the United States, Jamaica, and Malta, the sense of "two-party system" describes an arrangement in which all or nearly all elected officials belong to one of the only two major parties, and third parties rarely win any seats in the legislature. In such arrangements, two-party systems are thought to result from various factors like winner-takes-all election rules. In such systems, while chances for third-party candidates winning election to major national office are remote, it is possible for groups within the larger parties, or in opposition to one or both of them, to exert influence on the two major parties. In contrast, in the United Kingdom and Australia and in other parliamentary systems and elsewhere, the term "two-party system" is sometimes used to indicate an arrangement in which two major parties dominate elections but in which there are viable third parties which do win seats in the legislature, and in which the two major parties exert proportionately greater influence than their percentage of votes would suggest.
Political party
In dominant-party systems, opposition parties are allowed, and there may be even a deeply established democratic tradition, but other parties are widely considered to have no real chance of gaining power. Sometimes, political, social and economic circumstances, and public opinion are the reason for others parties' failure. Sometimes, typically in countries with less of an established democratic tradition, it is possible the dominant party will remain in power by using patronage and sometimes by voting fraud. In the latter case, the definition between dominant and one-party system becomes rather blurred. Examples of dominant party systems include the People's Action Party in Singapore, the African National Congress in South Africa, the Cambodian People's Party in Cambodia, the Liberal Democratic Party in Japan, and the National Liberation Front in Algeria. One-party dominant system also existed in Mexico with the Institutional Revolutionary Party until the 1990s, in the southern United States with the Democratic Party from the late 19th century until the 1970s, in Indonesia with the "Golkar" from the early 1970s until 1998.