Jihad is an Islamic concept meaning "to exert utmost effort, to strive, struggle"; has many meanings to the Muslim, both inward and outward; mainly used in the West to describe a "holy war" that some fundamentalist Muslims fight against non-Muslims or Muslims of other Islamic sects. The word "Jihad" is a transliteration of the Arabic word "جهاد".
Jihad as "struggle," is divided into two types, the greater Jihad and the lesser Jihad. The greater Jihad is the internal struggle against sin and temptation and to make one's self a better Muslim. The lesser Jihad is the physical conflict (historically understood as defensive struggle) against those who threaten the Muslim way of life. Many followers of Islam do not condone the use of jihad as a manner of securing converts.
Mention of Jihad in the Qur'an
Fight in the way of Allah against those who fight against you, but begin not hostilities. Lo! Allah loveth not aggressors. Qur'an 2:190
To those against whom war is made, permission is given (to fight), because they are wronged;- and verily, Allah is most powerful for their aid. Qur'an 22:39
Therefore if they withdraw from you but fight you not, and (instead) send you (Guarantees of) peace, then Allah Hath opened no way for you (to war against them). Qur'an 4:90
But if the enemy incline towards peace, do thou (also) incline towards peace, and trust in Allah: for He is One that heareth and knoweth (all things). Qur'an 8:61