A "classic" zombie is initially buried in a common man, whose body after his death in normal circumstances it is. Already in place of the funeral now, the cause for the "change" and the resurrection of the dead lie. If the deceased such as buried in a cursed Indian cemetery is certainly expected it sooner or later - to make a living form again - at least physically.
If the corpse is laid on an "average" cemetery to rest, there is - in literature and film - another way of life once again. That of the ritual. Means, of course, most vicious, magic is awakened the dead body of a spell caster. The thing is, that the undead is not after his resurrection, as in the first instance on their own, but is usually his "awakening" grateful subjects.
A third way of becoming-undead is quite fast and is different from the previous to the point that you did not previously, or is very short dead. Often result in failed biological experiments contaminated vapors released from living people for the same result as bewitched Indian burial grounds and dark Beschwörungsritualien.
to target an undead, I come in a later entry.
