There are the hard-core protesters, many of them with hoarse voices now from two weeks of shouting, and a goodly number with bandages on their heads from the stone-throwing battles against the pro-Mubarak mobs on Wednesday and Thursday last week. These are the people who will come up to foreign reporters, grab their arm, and with often a crazed look in their faces will shout "Mubarak must go" - and then turn away.
But there are also many ordinary Egyptians who have just come to be part, for a few hours, a whole afternoon maybe, of a carnival of political immunity. A place where they can say things - shout them even - that up to recently would have got them arrested immediately in any public place in Egypt.
We met one woman, Rasha al-Kady, who was holding up a poster calling for the abolition of Egypt's notorious Emergency Law, under which people can be held without charge. She described herself as a "stay-at-home-mom," and said she normally had no real interest in politics. But now that the demonstrators had staked out their space in Tahrir Square, she had felt compelled to come and join them. Her uncle had been detained once - had left home in the morning to buy a newspaper, and didn't come back.
"For a week, nobody knew where he was, not even his wife," she said. When I asked her how long she would stay in the square, she said she had to go home that evening to look after her son. What made her angry, she said, was that the government was presenting Mubarak's decision to step down in September as some great concession.
"It is my right, it is our right, to decide on who our president is," she said, getting agitated. "The government forgot they don't rule the country, they serve the country."
Rasha was leaving that evening, but not Mohammed Gamel, who was lying on a blanket under plastic sheeting. An engineer by trade, he was sleeping in the square, with his two sons. He was there, he said, because of his brother, Abdul Fateh, a 52-year-old man killed by a sniper's shot in the square last Friday.
Gamel took out a digital camera and showed us pictures of his brother's body from the morgue. "I will stay here - even if Mubarak leaves - I will stay, until they take down the whole system. Egypt should be a civilized country, we have a long history, the people deserve better."
He was shouting now, his eyes tearing up as he asked who would now look after his brother's six children, why would they shoot a teacher, a man who had helped so many others.
There is sadness and joy in Tahrir Square, debate and argument, hope for the future and anxiety about how to bring change to a country that has been ruled to the point of stagnation by one man and one party. But above all there is freedom here, freedom from the fear of reprisal if you speak your mind. And tens of thousands of Egyptians are exulting in that freedom, trying it on for size and liking the way it feels. It will be very hard to snatch that back from them, to turn the clock back to an era when nobody dared speak out. That will be one of the legacies of Tahrir Square.