Here is a look at Syrian opposition factions who began talks in Qatar on Sunday to forge unity crucial to gaining international respect and a better supply of weapons for their quest to oust President Bashar al-Assad.
* The Syrian National Council (SNC) is a largely foreign-based group which has been among the most vocal proponents of international intervention in the Syrian conflict. The SNC was formed in Istanbul in 2011 as an umbrella organisation to guide a democratic transition if President Bashar al-Assad fell, but has been accused by some of being under the thumb of Islamists.
* The main opposition bloc will seek broader relevance, SNC leader Abdulbaset Sieda said last month, by incorporating some 20 new groups into the organisation, including business groups and Kurdish, Turkmen and Syriac Christian representatives.
* It already includes The Damascus Declaration for Democratic Change group, Muslim Brotherhood, Local Co-ordination Committees, the Syrian Revolution General Commission (SRGC) activists' group, and various tribal and independent figures.
* The National Coordination Committee for Democratic Change (NCC), formed in September 2011, is made up of a number of left-leaning political parties, three Kurdish parties and independent political and youth activists. It is led by Hussein Abdul Azim. The group is against military intervention, including a "no-fly zone". The NCC does not call for overthrowing the Assad government, but rather a national dialogue.
* Free Syrian Army (FSA) - The Free Officers Movement and other military defectors joined forces in September 2011 and became the FSA, the main armed opposition group in Syria. It morphed into assorted militias using the FSA name, but with little central coordination. It includes army defectors and armed civilians. FSA leaders have admitted they are not in control of the proliferation of groups of armed civilians which have been operating under the FSA name. Leadership cropped up in neighbouring Turkey and exerted little authority over fighters on the ground. The FSA, which numbers around 80,000, has been working to resolve differences between rival local commanders and unite in a joint command based in Syria. In September 2012 FSA titular commander Riad al-Asaad announced he was moving his operation into rebel-held areas of north Syria for the first time.