Tens of thousands of people have been killed since the FARC rebels launched their guerrilla war in the 1960s. Millions more Colombians have been displaced.
The fighters say they are struggling for land and justice, against a corrupt political system.
But the Colombian government accuses them of turning to drug trafficking, kidnapping and extortion to fund their violent campaign.
Five key issues will be addressed when the main negotiations begin in Cuba next month: drug trafficking, land rights, ending hostilities, political integration and the rights of victims.
Al Jazeera's Gabriel Elizondo reports from Bogota, Colombia.