Ulster Unionist Party

The Ulster Unionist Party is the largest party in Northern Ireland and draws its support from the unionist community, the vast majority of whom are Protestant.

It was founded in 1905 when the Ulster Unionist Council was formed and in 1921, the party formed the government of Northern Ireland after the island was partitioned.

The UUP had become part of the Conservative Party but the relationship broke down when the Troubles emerged in the late 1960s and early 1970s.

Its leader David Trimble is also Northern Ireland's first minister and the party's position on the executive has been fraught with difficulty as for a while it refused to sit in government with Sinn Fein because the IRA had not begun to hand in its weapons.

The Secretary of State later suspended the assembly after the party threatened to collapse it over the same issue. After months of talks, the party agreed to go back into the Stormont government.

This uneasy pact is based on the assumption that the IRA is engaged in a process that will lead to decommissioning. The speed of progress on this is a cause of huge concern within the UUP.

The party holds 28 seats in the Northern Ireland Assembly, including four ministerial posts. However, two of its members do not take the UUP whip.

Democratic Unionist Party

The Democratic Unionist Party is the second largest unionist party in Northern Ireland.

It draws its support from the Protestant community and is fiercely opposed to the Good Friday Agreement and any moves towards involving the Republic of Ireland in Northern Ireland affairs.

It regards the agreement as nothing short of a threat to Northern Ireland remaining part of the UK. The DUP campaigned for a "no" vote in the referendum to gauge support for the Good Friday Agreement.

Ian Paisley has accused Ulster Unionist leader David Trimble of betraying unionism for signing the Good Friday Agreement.

Dr Paisley, who is also the leader of the Free Presbyterian Church, was elected to Westminster in 1970 and at that time he represented the Protestant Unionist Party which was formed in the late 1960s. In 1971 it was re-created as the Democratic Unionist Party.

Then the party announced it would be "right wing in the sense of being strong on the constitution" but "to the left on social policy". The party is vocally and strongly opposed to Sinn Fein's involvement in the new power-sharing executive even though there are two DUP ministers on the executive.

They took their seats to prevent them being given to other parties and do not attend cabinet meetings. The seats are currently being rotated through other DUP members as a rolling protest.

The DUP holds 21 seats in the Northern Ireland Assembly - including one held by Roger Hutchinson who defected to the party from the Northern Ireland Unionist Party in November 2000.

The party is defending the Westminster seats held by Mr Paisley in north Antrim, Peter Robinson in east Belfast, and William McCrea in south Antrim.

It is also hoping to do well in the marginal seats of North Belfast and the Ulster Unionist-held seats of east Londonderry and Strangford. But it has announced it will not contest seats held by anti-Agreement MPs.

Sinn Fein

Sinn Fein is the second biggest nationalist party in Northern Ireland and has grown out of the republican movement against a British presence in any part of Ireland.

The first party known as Sinn Fein was founded in 1905 declaring itself as working for the right of Irish people as a whole to attain self-determination".

The name translates into English as "Ourselves Alone" and the party's policies have long been based on a revolutionary socialist analysis of Irish history. The party has sought to position itself as the modern face of the republican movement, emphasising its support for the peace process and broader nationalist goals.

It is a signatory and supporter of the Good Friday Agreement signed in 1998, which created the devolved bodies and power-sharing arrangements between both of Northern Ireland's communities.

Its support for the agreement, coming four years after the IRA called its first ceasefire in almost 30 years, proved a major political turning point for republicans.

For the first time since partition of Ireland in 1922, the majority of the republican movement supported an agreement that delivered autonomy from London but fell short of the primary goal of complete Irish independence.

The agreement also enshrined the principle of cross-party consent into Northern Ireland politics, placing the onus on the politicians to find agreement among themselves.

The party's president, Gerry Adams, and its chief negotiator and education minister in the Northern Ireland Assembly, Martin McGuinness, both hold Westminster seats but do not take them up.

Since before the 1994 IRA ceasefire, the party has put greater emphasis on pursuing its aims via a political path, saying that it was incumbent on all sides in Northern Ireland to "remove the guns from Irish politics".

But the party's unionist critics say that Sinn Fein's assertions that it cannot speak for the IRA are a smokescreen - and that its leaders are doing nothing to deliver the arms decommissioning expected, in the very least, in the spirit of the Good Friday Agreement.

Gerry Adams has fallen out of favour with the US after not being invited to the White House during the St Patrick's Day celebrations. The snub followed the Northern Bank robbery, the biggest in UK history which was said to be connected to the IRA. Also, the murder of Robert McCartney, allegedly by IRA members has also turned public opnion against Adams, even though he has condemned the attack and has called for justice.