Jihad is two fold. Inner Jihad (greater Jihad) and outer jihad.
Inner Jihad is where one struggles with one self and strives to be a better person, muslim, human, etc. It is a battle within to improve oneself and fighting against the ills of one self, society or the whispering of the satan.
Outer Jihad is the physical Jihad for which permission has been given on order for one to defend themselves, their property, land, honor, etc. If anyone violates or try to violate your women, you have right to defend them. If anyone tries to take your land, kill you, or your kin, you have right to defend it all. If anyone invades your country, occupies it, do as they please, you have the right to fight back.
You can read more on jihad here:
http://muttaqun.com/jihad.html
btw, Jihad means struggle (whether with oneself or outside forces),it does NOT mean "holy war", a term coined by western media.