The Liberal Democrats, and their Liberal predecessors, have seen their fortunes rise and fall through a series of splits and re-alignments in British politics.
Nick Clegg became Lib Dem leader in December 2007
As a political philosophy, Liberalism grew up around a belief in the rights of the individual and freedom of choice.
This has developed into a modern political movement which gives the state an important role in achieving equal opportunities and ending poverty and discrimination.
What became known as the Liberal Party emerged in the middle of the 19th Century and after the election of 1868, William Gladstone formed the government that established the Liberals as a parliamentary force.
Despite a split over the issue of Home Rule for Ireland in 1886, the Liberals continued to vie for power with the Conservatives until World War I. In peacetime, however, splits in Liberal ranks helped a rapidly-growing Labour Party to become the official opposition.
In the wilderness
Over the next 40 years, the Liberal vote shrank and by the 1950s, had declined to just 2.5%, and there was talk of a merger with the Tories.
But under Jo Grimond, the Liberals began to rebuild at the grassroots, with a focus on community issues and what became known as "pavement politics".
By winning local council seats, party activists established a power base in cities like Liverpool, and success in local government revitalised their national ambitions.
Although their numbers at Westminster were still small, the close result in the February 1974 election led Prime Minister Edward Heath to invite them to join a coalition to keep the Conservatives in office.
Lib Dem popularity grew in the 1970s under Jeremy Thorpe
The offer was rejected by the Liberal leader, Jeremy Thorpe. Instead, Labour took power, and the Liberals were back on the fringes.
Mr Thorpe later resigned the leadership over accusations of an affair with a male model, Norman Scott, and was subsequently charged with conspiring to murder him. He was acquitted, but his political career was over.
Under Mr Thorpe's leadership though, the Liberals had increased their support at the general election from two million to six million, gaining almost 20% of the popular vote.
The party's new leader, David Steel, was able to capitalise on this growing influence by entering into the "Lib-Lab pact" and for a time supported Jim Callaghan's minority Labour government.
'Gang of four'
But the political landscape changed after Labour's defeat in 1979.
Four ex-ministers, the "gang of four", left to form the Social Democratic Party. The Liberals entered into an Alliance with the SDP, and in 1983, this strategy saw the two parties capture 25% of the popular vote.
But Mr Steel's optimism, urging conference delegates to "go back to your constituencies and prepare for government", did not translate into actual seats.
In 1988, the Liberals formally merged with the SDP, eventually settling on the name Liberal Democrats. Under a new leader, Paddy Ashdown, the party tried to present itself as a distinctive political force, pursuing radical policies.
It began to pick up support during the early 1990s when the Liberal tradition of capturing parliamentary seats at by-elections was successfully revived.
Paddy Ashdown succeeded David Steel in charge of the party
By 1997, the Lib Dems had become the second-largest party in local elections, controlling 55 councils and pushing the Tories into third place.
The party wooed voters by promising to put a penny on income tax to fund improvements in education, and placed considerable emphasis on environmental issues.
Under Mr Ashdown's leadership, the Lib Dems began to co-operate with the Labour government in areas where they had common goals, such as devolution.
But the relationship cooled under his successor Charles Kennedy, perhaps because of Labour's seeming lack of enthusiasm for reforming the voting system, long the objective of the third party.
The Lib Dems also took a stand against the Iraq war, putting them in line with much of public opinion.
In the 2001 election they won 52 seats, increasing this to 62 in 2005, taking a dozen seats from Labour in the process.
After the election, Mr Kennedy declared the Lib Dems the "party of the future", but the following January - after months of muttering and eventual rebellion from some members of his front bench team - he was forced to resign as leader after admitting to a drink problem.
He was replaced by Sir Menzies Campbell, but he was dogged from the off by claims that his age - 66 - made him too old to lead the party.
Charles Kennedy was forced to resign after admitting an alcohol problem
In October 2007, once it became clear that a snap general election was not on the cards, Sir Menzies quit, noting that questions about his leadership were "getting in the way of further progress by the party".
Treasury spokesman Vince Cable, who decided not to go for the leadership, stood in as acting leader and proved a hit at prime minister's questions.
But it was the younger Nick Clegg who would become leader - narrowly beating Chris Huhne in a leadership contest that December.
The then 40-year-old former MEP said he wanted to attract those voters who shared liberal values, but did not vote for the party.
His time as leader has seen the party's poll ratings stabilise. And the Lib Dems had been pressing the government on the issue of the Gurkhas' settlement rights before it was defeated on the issue after a high-profile campaign spearheaded by Joanna Lumley.
Former economist Vince Cable also saw his stock rise during the financial crisis - from his probing of the Northern Rock collapse to his repeated warnings about cheap credit, he was praised by Mr Clegg as a "twinkle-toed economic prophet".
In Crewe and Nantwich, Henley, Glasgow East, Glenrothes and Norfolk North the party failed to work its by-election magic but in the 2009 local elections, the party beat Labour to second place for the second year.
With talk of a hung parliament, there has been more focus on the Lib Dems but Mr Clegg is staying tight-lipped about the prospects of a formal alliance with either Labour or the Conservatives, aware that voters will not reward him for naming a price for power.