Haji Ali Baghdadi, who owns a small bazaar in Cairo's tourist Khan al-Khalili area, recalled the violence he witnessed in the 1990s that was caused by extremists.
"Those were the darkest days we have ever seen," Baghdadi said. "We saw innocent young men and women being killed before our own eyes because of extremism. At that time, tourists stopped coming to Egypt, and we closed our shops for a while. We lived through unforgettable poverty."
Like Baghdadi, many Egyptians were worried when they saw black flags similar to those used by al-Qaeda and other armed Islamist groups across the world during a demonstration in Cairo's Abbasiya Square earlier in April.
Some Egyptians said they are worried about the return of terrorism, like that practiced by a number of violent Islamist groups, foremost among them the Islamic Group and Islamic Jihad, in the 1980s and 1990s.
Many foreigners and Egyptians were killed in terrorist operations during that period. Former President Anwar Sadat was assassinated by Islamist groups in 1981, and in 1997 suspected Islamic Group militants killed over 50 people, mostly foreign tourists, in Luxor.
The Islamic Group renounced violence in 1997 and later issued ideological revisions in 2002 that prohibited killing civilians for any reason. After last year's demonstrations, the group formed the El-Benaa Wa El-Tanmia party and joined the political process.
Egypt's Islamic Jihad, which once included al-Qaeda chief Ayman al-Zawahiri among its ranks, also renounced violence in 2007.
Hossam Eldin Mahmoud, 36, an employee at a government agency, said he became extremely angry when he saw black flagcks target security facilities and natural gas pipelines. s instead of the Egyptian flag during the demonstration in Abbasiya Square.
"The revolution was staged for freedom, justice and tolerance among all Egyptians and for the sake of a new beginning," he said. "We did not get out of our homes a year and half year ago to topple Mubarak only to see the return of armed groups to Egypt."
The Pew Research Centre recently conducted public opinion polls that showed a large drop in al-Qaeda's popularity in Egypt and in other Arab countries. A poll published in late April showed that more than 71% of Egyptians oppose al-Qaeda's ideology and renounce the use of violence.
Ghaleb Mustafa, 31, an accountant for a private sector company, said Egyptians will not allow armed, violent Islamist groups to return to the country "after they were expelled more than 10 years ago".
He said Egyptian youth have greater awareness about the ways to become politically active without resorting to violence.
"There are various ways to take part in changing the country," Mustafa said. "Young people know that they do not need to use arms or adopt extremism to spread the teachings of Islam or Islamic sharia. Most of the existing parties depend on young people who I think will resist any armed group that harms Egypt or kills Egyptians."
Black flags appeared for the first time in Sinai in July 2011 when several masked men surrounded the Arish police station in northern Sinai and opened fire on security forces. Two officers and three civilians were killed, and 16 others were wounded. The armed group that attacked the police station carried black flags reading, "No god but God and Mohammed is His Prophet".
Egyptian security forces from time to time engage in battles with armed groups in Sinai, whose attacks target security facilities and natural gas pipelines.
Some groups have also emerged online, such as the Promotion of Virtue and Prevention of Vice Committee, which has called on young Egyptians to implement Islamic law in all parts of Egypt.
Adel Othman, 24, an engineer who supports the Salafist movement in Egypt, said the use of violence to achieve political goals and impose an opinion on others is contrary to Islamic sharia, which advocates tolerance.
He said attaining goals through legitimate means, notably through elections and a peaceful transition of power, are the only permissible methods for any Islamic faction.
"We do not need al-Qaeda to teach us how to build Egypt," Othman said.
Othman said he participated in the Abbasiya Square demonstrations, and he and a group of colleagues who support the Salafist movement rejected the use of black flags.
"Egypt has only one flag that all Egyptians must gather around," he said. "There is no discrimination among Egyptians based on their religion."
Mahmoud al-Bassel, 50, a secondary school teacher, spoke about how to counter the spread of al-Qaeda ideology in Egypt.
"Increasing political participation among young people and finding solutions for unemployment problems will shut off the resources of extremism in Egypt and will encourage young people to get busy building their nation," he said.
He said poverty, illiteracy and an undemocratic regime like that of former President Hosni Mubarak were the main ingredients that provided fertile soil for extremist groups.