Jahad In Islam:
From the Arabic root meaning “to strive,” “to exert,” “to fight”; exact meaning depends on context. May express a struggle against one's evil inclinations, an exertion to convert unbelievers, or a struggle for the moral betterment of the Islamic community.

Today often used without any religious connotation, with a meaning more or less equivalent to the English word crusade (as in “a crusade against drugs”). If used in a religious context, the adjective Islamic or holy is added.

Jihad is the only legal warfare in Islam, and it is carefully controlled in Islamic law. It must be called by a duly constituted state authority, it must be preceded by a call to Islam or treaty, noncombatants must not be attacked, and so on.

To justify the struggle against their coreligionists, extremists branded them unbelievers for their neglect in adhering to and enforcing a particular interpretation of Islam. Contemporary thinking about jihad offers a wide spectrum of views, including conservatives who look to classical Islamic law on the subject and radicals who promote a violent jihad against Muslim and non-Muslim rulers.