Extremists follow the same core values, which are the total opposite of orthodox islam (sunna wal juma). An insulting term, "wahhabi" is often used to describe such people in the mainstream muslim communities now-a-days, which derives from Muhammad ibn Abd al Wahhab. more on muhammad wahhab http://en.wikipedia.org/wiki/Muhammad_ibn_Abd_al_Wahhab All extremists claim to be purifying, and restoring original Islam, but in actuality they're deviating from it. Osama Bin Laden and Al-Zakhari were strong followers of "Qutbism" more on qutbism To learn more: http://en.wikipedia.org/wiki/Qutbism Qutbism believes in offensive wars instead of the traditional defensive wars, which traditional orthodox muslims follow. The Taliban (Mullah Omar), Qutbists (Osama, Zakhari etc..) are all "wahhabis" because all share the same core values, which are radical in belief. Wahhabi's say they're "Salafi" muslims, but in actuality they're not. People often get confused with the terms "salafi" and "wahhabi" and often categorize them as the same. Wahhabism is a particular orientation running within Salafism, but it isn't real salafism, and the wahhabi's try to pull the wool over people's eye's by referring to themselves as salafi's when they're really not (and it shows through their terrorist actions). more on salafi's http://en.wikipedia.org/wiki/Salafi All branches of extremsim share the same core values, and they're referred to as "wahhabi's" by the orthodox muslim communities.