On 4 July 1776, 56 men gathered in PhiladelphiaThe largest city in Pennsylvania, USA, with a population of one and a half million. to sign a document. A year earlier, they had voted to break free from the United Kingdom and launched into war. But this document, the Declaration of Independence, explained to the world why they did it.

It is one of the most celebrated manifestosA statement published by a person or group of people, especially a political party, or a government, in which they say what their aims and policies are in history. And it helped to set a blueprint. Manifestos have been a major part of democratic politics ever since. Every party in the upcoming UK general election is expected to publish one.

A political manifesto is a document containing the policies party plans to enact if put into power. According to the think tankA research organisation focusing on a certain topic, such as climate policy or education. They often produce information used by businesses, governments and big organisations. Institute for Government, they are a "party's contract with the electorateAll the people eligible for voting in a country.."

Election promises can have a big impact on a government's behaviour. Buried on page 30 of the 2015 ConservativeHolding traditional values, and in a political context, favouring policies such as private ownership. manifesto, for instance, was a line that changed Britain forever. It promised a "straight in-out referendum on our membership of the European Union by the end of 2017".

Broken manifesto promises can become a sticking point with voters. In 2010, Britain's Liberal DemocratsAlso known as the Lib Dems, a liberal political party in the UK. party won 57 seats in the House of CommonsThe democratically elected house of the UK Parliament. It consists of 650 Members of Parliament.  and went into coalition with the Conservatives. Before, they had promised to scrap university tuition fees. Once in government they voted to raise them instead. A wave of protest followed. In the next election they lost 49 seats.

Yet some say this is the exception rather than the rule. Boris JohnsonThe Conservative Prime Minister of the UK and head of the government from 2019 to 2022. broke at least eight manifesto promises during his three years as prime minister.¹ But his downfall came about for other reasons.²

In Britain, manifesto promises are not binding. Of 39 key commitments in the 2017 Conservative manifesto, only a third were on track to be implemented by the next election in 2019. A fresh vote pushes old manifesto promises into the dustbin. 

Manifestos also face apathyLack of interest or enthusiasm. . A 2017 poll found that 67% of the UK public - just over two-thirds - either do not read manifestos or do not know what they are.

Though many people do not read them directly, they do influence public opinion. Manifestos influence the tone of media coverage. A policy that the press does not like can lead to outrage.³ Parties need to think hard about what to put in - and what to leave out.

Do they really matter? 

Yes: Manifestos may not be binding. But they give the public and the press some idea of what to expect, and a government a mission to try to follow. And major breaks can cause scandal and discontent. 

No: They are all talk. They provide discussion points and capture some voters. But parties are not forced to follow them. Losers rip them up and start again. And winners can do as they please.

Or... It depends on the party - and the situation. Sometimes events make manifesto promises impossible to keep. And policies that sounded good before an election can turn rotten as outside factors change.