If you read Arabic and want a degree in jihad, click on www.al-farouq.com/vb/. If you're lucky--the site disappears and reappears--you will see a post that belongs to the Global Islamic Media Front (GIMF). It announces the "Al Qaeda University of Jihad Studies." According to Ahmad al-Wathiq Billah, the GIMF "Deputy General Emir," students "pass through faculties devoted to the cause of the caliphate through morale boosting and bombings," and the site offers specialization in "electronic, media, spiritual and financial jihad."

The Internet has long been essential for terrorism, but what has surprised experts is the growth of such Islamist (radical Islam) and jihadist sites. Their continuing rise suggests that recruitment for a "holy war" against the West could proceed unabated, despite capture of key leaders.

According to Gabriel Weimann, a professor of communications at the University of Haifa in Israel, the number of all terrorist Web sites--those advocating or inciting terrorism or political violence--has grown from a dozen in 1997 to almost 4,700 today, a nearly 400-fold increase. (By comparison, the total number of Web sites has risen about 50- to 100-fold.) The enumeration includes various Marxist, Nazi and racist groups, but by far the dominant type, according to Weimann, is the Islamist-jihadist variety, which accounts for about 70 percent.

The war in Iraq provides plenty of motivation for radicals, and the Internet appears to be facilitating them, even if legitimate governments shun them. "We are talking about groups that are opposed and persecuted all over the Arab and Muslim world, so the Internet becomes the only alternative to spread their messages," says Reuven Paz, director of PRISM (Project for the Research of Islamist Movements), a watchdog group in Herzliya, Israel. The spread "is like an attempt to create a virtual Islamic nation."

Scott Atran, a research director at the Jean Nicod Institute of the CNRS in Paris, studies the group dynamics of terrorists. He notes that the attackers of Madrid, London and Bali were autonomous groups, like "swarms that aggregate to strike and then vanish." The open, anarchic structure of the Internet supports this "chaotic dynamics" modus operandi as a way for militants to recruit new members and look for goals or inspiration. "Without the Internet, the extreme fragmentation and decentralization of the jihadi movement into a still functioning global network just would not be possible," Atran argues. "I think we can expect more independent attacks by autonomous groups because of the Internet."

Atran cites the Madrid train bombings on March 11, 2004, as a good example: a computer of one of the attackers showed evidence of systematic downloading from the same site that delivered a document entitled "Jihadi Iraq: Hopes and Dangers," which had circulated on the Net some months before the massacre. Among other charges, the document called for attacking Spain to force a withdrawal of that nation's troops from Iraq.

Atran, who has interviewed several radical jihadists, says that the Internet has spread a homogenized, flat notion of Islam, one that has little to do with Islamic tradition. The militants express a message of martyrdom for the sake of global jihad as life's noblest cause. "I was very surprised to find, from the suburbs of Paris to the jungles of Indonesia, that people gave to me basically the same stuff, in the same words," Atran says.

Combating the problem might come at the expense of the freedom expected on the Internet. Weimann has argued that data mining could sniff out jihadists or remove information before would-be terrorists see it. Marc Sageman, a psychologist at the University of Pennsylvania and a former CIA officer, notes that the nature of Islamist-jihadist sites could be turned against them. "In jihad, with so many Web sites, you have many potential messages, and you do not know what is true," he remarks. This lack of authenticity, he notes, could serve as a basis for a misinformation campaign to foil jihadists.

Atran thinks it may be possible to fight the virulent ideas not just with a fist but also with an outstretched hand. The chat room could serve as a forum for life-affirming ideas as it does for terrorist ones. Convincing jihadists of alternative values would be a long process, he admits. But "I have seen groups of mujahedeens" transformed from fighters to community helpers. If that conversion works in physical space, he says, "I do not see any reasons why we cannot do that in cyberspace."