Many media outlets have wrongly reported that the black flag that people taken hostage in a Lindt cafe in Sydney were forced to hold up by an alleged gunman was an Islamic State flag.
In fact, the flag raised by the hostages is written in white coursive Arabic characters and reads: "There is no God but Allah, and Muhammad is his messenger". That is the basic creed statement in Islam lifted from the Koran and known as the Shahada.
The statement can be a harmless symbol and is widely used by Muslim communities across the world in their daily lives and in Islamic prayers. The Shahada, which translates to "testimony", appears in the national flags such as the Saudi Arabia official flag and different versions of Afghanistan flag from 1992 and 2001. The Saudi version, which derives from the Wahhabi religious movement, uses a green rather than a black blackground.
However, the flag is also used by Islamist militant groups fighting in Syria, such as the al-Qaeda linked al-Nusra front, and Syria and Iraq, such as the Islamic State (Isis). Boko Haram, the Islamist militant group fighting in Nigeria, also uses a version of the Shahada.
These groups portray themselves as the true Islam representatives and guardians of the true faith and therefore use the Shahada to fight "infidels".
Al-Nusra's flag is the most similar version the one held in the Lindt cafe, although it has the Jabat al-Nusra name written underneath the Shahada.
The Shahada is the first of the five pillars of Islam.
BBC's security correspondent Frank Gardner said the gunman "got the wrong flag" and the hostage siege "does not look like a sophisticated plot".
As pointed out by many experts, the black flag in the Sidney cafe can be representative of any Islamic or Islamist groups: