Islamists? Jihadists? Maybe NOT..
"The people demand the fall of the regime!" they chanted in their thousands in Cairo's central Tahrir square for several hours on the "Day of Wrath" that started a wave of protests across the country on Tuesday.
"An electrifying chant. I never heard it before," university graduate Sami Shabaan, 24, said, joining in and shouting it over and over. "We are not leaving here until the regime falls."
Egyptian and other authoritarian Arab governments have often warned that the choice was 'us or them' - meaning Islamist extremists - a threat that shored up support from wary Western leaders. These protesters suggested otherwise.
When one bearded man stood up in the middle of Tahrir to give a sermon on Islam to the crowd on Tuesday, he was quickly asked to tone it down.
"This is not about religion, it is about Egypt," several people around him said.
A few protesters shouted Islamic chants were held back by colleagues who said the chants must remain secular to unite a crowd that Christians had also joined.
"We are Egyptians who want change and better lives," said 36-year-old government worker Mursi Minawy, who came out with his wife and two children to participate.
Many protesters, organised by Internet campaigns through social media networks such as Facebook and Twitter, are young.
Two thirds of Egypt's 80 million people are below the age of 30, and many of them have no jobs. About 40 percent of Egyptians live on less than $2 a day.
For months, protesters from labour unions and opposition groups have held a series of small disparate demonstrations demanding higher wages in their individual sectors and help for the millions of poor Egyptians.
But this time, it is different. Emboldened by the protests in Tunisia that swept the president from power, there is now a much broader demand - an end to Mubarak's 30 years in power.
"This is a turning point in protest culture," Amr Shobky, a political analyst who joined the protest, said. "Ordinary Egyptians have taken to the streets with one collective demand that goes beyond provisional ones like minimum wages".
Khalil Anani, a political analyst based in London, said: "The determination of ordinary civilians is more significant here than any religious motivation."
In Cairo, the young, savvy protesters have played a cat and mouse game with the state security apparatus, swerving down back streets, dispersing and regrouping at lightning speed to dodge arrest.
In Suez, in the east of the country, the protests have been more violent, with demonstrators throwing rocks and petrol bombs as they face off against police firing teargas.
"Ordinary citizen turnout is the yardstick as to whether the protests will keep gaining momentum," Shobky added.
The Muslim Brotherhood has long been seen as the country's biggest opposition group capable of mustering supporters to challenge the state but critics have said it has often refrained from taking that risk.
It has stayed largely on the sidelines of these protests, although many of its members have been taking part.
"The street is leading the demonstrations, not the parties. The Muslim Brotherhood is there but cannot claim domination over youth activism," Anani said.
Egyptian protests usually draw only a few hundred people. The large numbers and coordination across several cities have given this week's events a force unprecedented since Mubarak took office in 1981.
Egyptians of all backgrounds and ages have taken part but university graduates made up the bulk of the crowd at the start of the protests.
"We are here to change Egypt," yelled Samia Metwali, 22. "Teargas or bullets will not stop the power of the people."