Formerly Jabhat al-Nusra, then Jabhat Fateh al-Sham, it is a group of allied factions, including Jabhat Fateh al-Sham, Liwa al-Haqq, Jabhat Ansar al-Din and Jaysh al-Sunna. At the start of the Syrian war, Jabhat al-Nusra was formed in 2012 by ISIL (ISIS), from which it split a year later and declared allegiance to al-Qaeda.

Anti-government forces have taken control of Syria's second city Aleppo. But who are the rebels and what are their goals? One key player is the group Hayat Tahrir al-Sham - or HTS, which already controls much of northwest Syria and is expanding its reach.