Who's involved in the rebels' Aleppo offensive? The cliff-notes
Syria's civil war started out in 2011 and was relatively simple to understand. Following a series of public demonstrations against President Bashar al-Assad and his regime, civil unrest and disobedience started to snowball into armed conflict as the regime responded with brutal force.
Various armed rebel groups started to form at this time out of a view that Assad would only be removed by force and to defend anti-regime areas.
These rebels were then later bolstered by Syrian army commanders who broke away from Assad and founded a newly formed rebel army, known as the Free Syrian Army (FSA).
This united force began to fragment however, under the pressure of international pressure and in-fighting. Various leaders, whether out of distrust of their own comrades or vanity, started to splinter off and form their own break-away groups.
These brigades, taking part in the Aleppo siege, are under the title 'Fatah Aleppo' and are, for the most part, connected to the original Free Syrian Army.
Other groups started to form after the outbreak of the Syria war, connected with al-Qaeda and other forms of Salafi-Islamist ideology. These groups recently formed a separate coalition, called the Jaish al-Fatah, or 'Army of Conquest'.
These two coalitions do not usually fight together, although they are in communication with one another. These two coalition forces are now ultimately united by a common enemy in the Syrian regime and its Russian allies and taking the lead in the Aleppo offensive.Fatah Aleppo
Jaish al-Nasr (Army of Victory) - a group of sixteen different rebel groups, linked to the FSA.
Jaish al-Mujahedeen - a group of Islamist fighters who were set up to fight Islamic State group (IS). Also allied with Turkey against the Kurdish group, PKK.
Division 13 - a small group connected with the Free Syrian Army - founded by Lt. Col. Ahmad al-Saoud
North Division - founded in September 2012 by Lt. Col. Fares al-Bayoush
Central Division - formed in September 2015 as a formation of two different FSA groups.
Jaish al-Tahrir (Liberation Army) - a medium sized group of five FSA-linked groups, formed in February 2016, led by Mohammad al-Ghabi.
Jaish al-Islam (Army of Islam) - a large coalition of Islamist and Salafist brigades that rejected the FSA.
Fastaqim Movement - an Aleppo-based group of FSA brigades - led by Saqr Abu Quteiba.
1st Regiment - previously a member of the Tawhid brigade, currently fighting in the centre of Aleppo and the surrounding area.
Jabhat Shamiyah (The Levantine Front) - a Salafi group of rebels, led by Abu Amr, a commander of Ahrar al-Sham.
Jaish al-Fatah (Army of Conquest)
Jabhat Fatah Sham (JFS) - formally known as al-Nusra Front. Sometimes referred to as al-Qaeda in Syria, but the group announced a formal split from al-Qaeda in July 2016. Fighting against the Syrian regime in order to establish an Islamic state.
NB. UN envoy for Syria, Staffan de Mistura, famously called on Fatah al-Sham to withdraw from the siege of Aleppo, saying that to do so would improve the chances of a ceasefire.
Ahrar al-Sham (Freedom of the Levant) - A coalition of large number of Salafi and Sunni Islamist brigades, and one of the largest rebel groups in Syria. Allegedly funded by Saudi Arabia, it is allied with the Free Syrian Army (FSA) but has not joined the coalition.
Harakat Nour al-Din al-Zinki - Named after a 12th century emir from Aleppo. A medium-sized Sunni Islamist group of fighters, led by Tawfiq Shahab al-Din. Mainly fighting in and around Aleppo.
Ajnad al-Sham (Soldiers of the Levant) - A small coalition of various Islamist battalions and brigades that was mostly active in the siege of Darraya.
Jaish al-Sunna - A small Salafi group based mainly in Homs, led by Ammar Bouqai.