Since 1945, three parties have dominated German politics: the Christian Democratic Union (CDU), with its southern sister party the Christian Social Union (CSU) on the right, and the Social Democratic Party (SPD) on the left.
The Free Democratic Party (FDP), a much smaller, liberal party, would often enter into coalition with either the CDU/CSU or the SPD. In the 1980s, the Greens emerged as a political force. They have been junior partners in the two SPD-led governments of 1998 and 2002.
In the elections to be held on 18 September, a new Left Party comprising former communists and disaffected SPD supporters is also fielding candidates.
CHRISTIAN DEMOCRATIC UNION
The conservative CDU has enjoyed the longest stretches in power of all the parties since World War II. It led the government from 1949-1969 and from 1982-1998.
The CDU and CSU have always banded together
Formed in 1945, it brought together a number of smaller Catholic and Protestant parties that had resisted National Socialism. All believed in a dominant role for the market while at the same time advocating state intervention to prevent social hardship.
CDU foreign policy was forged by the first federal chancellor, Konrad Adenauer. It is based on strong support for Nato and European integration. Under Helmut Kohl, the party presided over German reunification.
Mr Kohl was ousted by the SPD's Gerhard Schroeder in 1998 and the party suffered further the following year when a scandal over illegal party funding became public. It directly involved Mr Kohl, who refused to reveal the provenance of DM2m (1bn euros) worth of donations. The affair also resulted in the resignation of party chairman, Wolfgang Schaeuble, in 2000. He had been Mr Kohl's chosen successor. Mr Schaeuble was replaced by Angela Merkel, who is now seeking the chancellery.
CHRISTIAN SOCIAL UNION
The Christian Social Union, the CDU's sister party, stands only in Bavaria. Established in 1946, the CSU is more conservative than the CDU - particularly on issues such as abortion and immigration.
It was led between 1961 and 1988 by Dr Franz Josef Strauss, then by Theo Waigel, the finance minister in the Kohl government, from 1988-1998. Mr Waigel was succeeded by the premier of Bavaria, Edmund Stoiber in 1998. Mr Stoiber stood as the joint CDU/CSU candidate for chancellor in 2002 but was narrowly beaten by Mr Schroeder. Relations are not always easy between the CDU and CSU and there is said to be tension between Mrs Merkel and Mr Stoiber.
SOCIAL DEMOCRATIC PARTY
Formed in the late 19th Century, the SPD was originally a Marxist party. It became the biggest political party in Germany in the years of the Weimar Republic, in 1919-33, before being forced into exile during the Nazi period.
Mr Schroeder took his party down a "third way"
In the post-war period, its politics became ever more moderate, and in 1959 it disavowed its Marxist past. It dropped its opposition to membership of the European Economic Community and Nato and accepted the country's post-war "social market economy" strategy.
With the party repositioned as left of centre, leaders such as Willy Brandt and Helmut Schmidt won mainstream support. The party was in government from 1966-1969 as the junior partner in a "grand coalition" with the CDU/CSU. From 1969-1982 it was the main governing party with the FDP as its junior partner.
It then entered a 16-year period in opposition during the Kohl years. In 1998, the SPD under Gerhard Schroeder won a convincing victory and went into government with the Greens. The Red-Green coalition was narrowly re-elected in 2002.
The Greens began life as a loose coalition of local environmental groups who did not establish themselves as a federal political party until 1980. The party put environmental issues at the top of the agenda and emphasised pacifism, opposing nuclear weapons and Nato membership.
Mr Fischer is one of Germany's most popular politicians
The Greens succeeded in reaching the 5% of the vote needed to take parliamentary seats in 1983 and again in 1987. It was not however until 1998 that they had their first taste of government as a junior partner in coalition with the SPD. By this point the Greens had developed from concentrating solely on environmental and pacifist goals to addressing the full spectrum of political issues.
There were divisions. Military intervention in Kosovo and Afghanistan caused anger among those members who held dear the party's pacifist roots. However, both were strongly supported by Green Foreign Minister Joschka Fischer, one of the country's most popular politicians.
FREE DEMOCRATIC PARTY
The Free Democratic Party comprises liberals who advocate free market economics and reduced government intervention. It was formed in 1948, although smaller liberal predecessors can be traced back to the 19th Century.
In the 1950s it found support mainly among the self-employed, small town conservatives and some farmers, but it later broadened its appeal to white-collar workers. It has never managed to garner enough support to challenge either the SPD or CDU but has played a prominent role in German political life as the kingmaker in coalitions.
Support for the party fell in the 1990s and the choice in May 2001 of a young new leader, Guido Westerwelle, was intended to broaden its appeal.
The party provoked controversy in the 2002 elections, when the then vice-chairman, Juergen Moellemann, published a pamphlet regarded as anti-Semitic and an attempt to court the right-wing vote. Mr Moellemann was forced to leave the party and committed suicide in May 2003. Since then the FDP has concentrated mainly on calling for economic reform. It favours more far-reaching reforms than either the SPD or CDU.
THE LEFT PARTY
The Left Party is a new political alliance formed earlier this year combining the Party of Democratic Socialism (PDS) with the new Labour and Social Justice Party (WASG). The parties have a joint manifesto and have agreed not to compete against one another in any constituency. This is relatively unproblematic since PDS supporters are mainly in the east and WASG supporters in the west.
Mr Lafontaine and Mr Gysi hope for a joint breakthrough
The Party of Democratic Socialism (PDS) is the successor to the former Socialist Unity Party of Germany (SED), the ruling party in the communist German Democratic Republic (GDR). Its support remains primarily in east Germany, where it can attract up to one-fifth of voters, compared with only 1% in the west. In the 2002 general election it gained 16.9% of the vote in eastern Germany and 1.1% in western Germany, so that its share at the national level was only 4%.
This is below the 5% threshold for proportional representation in parliament but since two of its candidates gained a majority of votes in individual constituencies it has two MPs. Its leader is Gregor Gysi, a charismatic and popular figure. He has nonetheless been touched by scandal in the past, including allegations that he was a Stasi informant and later that he misused air miles.
The PDS has been joined by the small West German Labour and Social Justice Party. The WASG association began in July 2004 and was officially set up as a political party in January 2005. It first ran in local elections in May 2005 and gained 2.2% of the vote. It contests what it calls the "neo-liberal consensus" of the larger parties. It primarily appeals to disaffected SPD voters and its principal figure is Schroeder rival Oskar Lafontaine.
There are three far-right parties: the nationalist German People's Union (DVU), the neo-Nazi National Democratic Party (NPD) and the Republikaner. The NPD and DVU enjoyed some success in state elections in 2004, when the NPD won 9.2% of the vote in Saxony and the DVU 6.1% in Brandenburg after agreeing they would not field candidates in competition with each other. The government tried but failed to ban the NPD in 2003. None of the far-right parties are represented in the parliament and are not likely to reach the 5% threshold in this election.