F.A.R.C. (Fuerzas Armadas y Revolucionarias de Colombia)
REVOLUTIONARY ARMED FORCES OF COLOMBIA
The Farc is the oldest and largest group among Colombia's left-wing rebels - and is one of the world's richest guerrilla armies.
The group was founded in 1964, when it declared its intention to use armed struggle to overthrow the government and install a Marxist regime.
But tactics changed in the 1990s, as right-wing paramilitary forces attacked the rebels, and the Farc became increasingly involved in the drug trade to raise money for its campaign.
According to a US justice department indictment in 2006, the Farc supplies more than 50% of the world's cocaine and more than 60% of the cocaine entering the US.
The Farc, which is on US and European lists of terrorist organisations, suffered a series of blows in 2008. Several leaders died, including the top commander, Manuel Marulanda.
The most dramatic setback was the rescue by the military of 15 high-profile hostages. The hostages had long been seen as a key element in the rebels' attempts to exchange their captives for jailed guerrillas.
However, the rebels still control rural areas, particularly in the south and east, where the presence of the state is weak.
