Key players in the EU referendum debate: Who wants to stay and who wants to leave?
Cross-party group Britain Stronger in Europe has launched its campaign to get the public to vote to stay in the European Union in the forthcoming referendum by warning voters that opting for a Brexit would be a "leap in the dark".
Championing the other side of the argument are two separate no campaigns 'Vote Leave' and Leave.EU which launched earlier thsi month with the message that "we must end the supremacy of EU law over UK law".
Here's all you need to know about the campaigns and the key aims behind them.
Britain stronger in Europe
What does it stand for?
The campaign to stay in the EU.
Chair of the campaign Lord Rose has said he want the UK to keep its relationship with the EU as he says it is "not in our national interest" to retreat from our position of influence in Europe and leave.
Who are the significant figures backing the campaign?
Lord Rose - Former Marks & Spencer chief Rose has been elected chair of the campaign. The prominent business figures says he voted to join Europe nearly 50 years ago and would still vote the same way now if given the choice again.
Karren Brady - Vice-chairwoman of Premier league team West Ham United and Apprentice star. Baroness Brady has raised concerns that "no ones ever left the EU so you can't quantify the loss".
June Sarpong - A panellist on ITV's Loose Women Sarpong chaired the campaign's first public debate over why the UK should stay in the EU
Who are the other significant supporters of the campaign?
Sir John Major - Former Prime Minister, Gordon Brown- Former Prime Minister, Tony Blair- Former Prime Minister, Lord Mandelson - Labour grandee, Danny Alexander - Liberal Democrat former Treasury minister, Caroline Lucas - Green MP, Damian Green - Tory former Home Office minister, Chuka Umunna - ex-Labour frontbencher
Why do they want the UK to exit the EU?
It believes that leaving the EU would have a negative impact on the UK economy, diminish the country's influence and put the nations security at risk.
Vote Leave
What does it stand for?
The campaign to leave the EU.
It thinks the EU has too much control over Britain on things like trade, tax, economic regulation and energy and that he nation should break away.
Who are the significant figures backing the campaign?
Peter Cruddas - Former Tory treasurer and banker. One of the millionaire donors helping to fund the capmpaign.
Steve Baker- Conservative MP who is helping chair the Vote Leave campaign. Believes voters should take courage from the Greeks and look to "safeguard their own national interest".
Kate Hoey - Labour MP who is co-chairing the Vote Leave campaign. Hoey says it is time to "take back control of our countries' laws to the British parliament".
Who are the other significant supporters of the campaign?
Douglas Carswell - Tory defector and Ukip's only MP, Owen Paterson - Former environment secretary, Bernard Jenkin - Backbench Tory MP, John Mills - Labour's biggest donor, Stuart Wheeler - Tory donor and ex-Ukip treasurer, Joe Foster - Businessman and Reebok sports brand founder, Luke Johnson - Ex-Channel 4 chairman
Why do they want the UK to exit the EU?
They basically think the EU has too much control over Britain on things like trade, tax, economic regulation and energy.
When is the referendum?
David Cameron has promised to hold the referendum by the end of 2017.
But there have been suggestions that it could be held as early as next year.
The prime minister has said he wants to renegotiate Britain's relationship with the EU before putting the new arrangement to the public.
What will the question be?
British, Irish and Commonwealth citizens - who over the age of 18 and are living in the UK or have been residing overseas for under 15 years - are likely to be asked:
There is still no date set for the European Union referendum, which may be as much as two years away, and the Bill paving the way to the vote has yet to complete its passage through Parliament.
Democracy watchdog the Electoral Commission must designate one organisation on each side as the "lead campaigner", with benefits including an increased spending limit, TV broadcasts, publicly-funded grants, free mailing and access to meeting rooms.
But there is no limit to the number of groups which can campaign, and more organisations are expected to spring up on both sides to represent different shades of pro- and anti-EU opinion. Anyone can spend up to £10,000 on a referendum campaign, but those passing this limit must register with the Electoral Commission.
So who's who in the referendum debate?
:: Leave.eu is backed by Ukip leader Nigel Farage and financially supported by the eurosceptic party's major donor Arron Banks.
It has business backing from "ambassadors" including entrepreneurs Richard Tice and Jim Mellon, bookshop boss Toby Blackwell, stockbroker Jonathon Seymour Williams and solicitor John Banks.