The Scottish National Party, headquartered in McDonald Road, Edinburgh, is the second most voted-for party behind Labour north of the border and campaigns primarily on a ticket of Scottish independence.
The SNP have a generally centre-left political ideology nowadays but, originally, it was formed as a marriage of two smaller parties from opposite sides of the centre ground, creating certain long-standing tensions among some more outspoken members.
The public face of the SNP is its leader, Alex Salmond, who has not been backward in coming forward about the party's plans for a referendum on Independence should it take overall control in the Scottish Parliament in this year's general election, saying it would happen within months.
Some of the major pillars of the SNP ideology include the equitable redistribution of wealth, free education, higher public sector wages and nuclear disarmament. The party also foresees an independent Scotland taking its place as a full European Union member state, also adopting the Euro as its currency.
Perhaps somewhat surprisingly for a nationalist party, the SNP doesn't preach a message of republicanism overtly, although a significant number of its members do harbour anti-monarchist sentiments.
The SNP has long been politically close to the Welsh nationalist Plaid Cymru Party, in fact the two party's MPs work in partnership in the House of Commons to increase their clout; the party applies the same logic to the European Parliament, forming coalitions with the Greens.