From an NYPD document about radicalization of so-called “homegrown” threats:

The Internet is a driver and enabler for the process of radicalization

1. In the Self-Identification phase, the Internet provides the wandering mind of the conflicted young Muslim or potential convert with direct access to unfiltered radical and extremist ideology.
2. It also serves as an anonymous virtual meeting place—a place where virtual groups of like-minded and conflicted individuals can meet, form virtual relationships and discuss and share the jihadi-Salafi message they have encountered.
3. During the Indoctrination phase, when individuals adopt this virulent ideology, they begin interpreting the world from this newly-formed context. Cloaked with a veil of objectivity, the Internet allows the aspiring jihadist to view the world and global conflicts through this extremist lens, further reinforcing the objectives and political arguments of the jihadi-Salafi
   agenda.
4. In the Jihadization phase, when an individual commits to jihad, the Internet serves as an enabler—providing broad access to an array of information on targets, their vulnerabilities and the design of weapons.