A ghoul is a mortal human, fed with vampiric vitae. Ghouls make loyal servants, retainers, companions and mortal muscle. Vitae grants them limited access to vampiric Disciplines and also halts their aging, while at the same time ensuring their loyalty through Blood Addiction and the Vinculum. Ghouling, the process of making a ghoul, is frowned upon as a breach of the Masquerade - as it creates mortals who are aware of the existence of vampires - but ghouling is tolerated, for the most part, because ghouls are generally loyal and, more importantly, they can perform tasks for their masters (Domitors) during the day, whilst Kindred are asleep.
Creating a ghoul involves two steps, taken at the same time: feeding the prospective candidate some of his master's vitae, and the vampire concentrating his will to alter the ghoul's body - in game terms, expending one point of his Willpower. From that moment on, the ghoul has all the benefits and drawbacks of being a ghoul, and will retain such as long as they are given vitae and Willpower is spent. Unlike the first time, either party can spend the Willpower point on subsequent feedings.
Ghouls require vitae every month to maintain their state and to halt the passage of time. If they do not get their monthly feeding, they lose access to their Disciplines and the clock starts running again; they age the equivalent of a year for each day that passes without vitae in their system until they've caught up with what they've missed.
Most ghouls are loyal servants to the vampire feeding them (the Vinculum helps to assure this), but some break free of their masters and serve - or hunt - other vampires to maintain their state. For this reason, many vampires do not allow their ghouls to exert the necessary will to maintain their state, nor do they tell them it's possible. Better to leave them ignorant than give a loose cannon reasons to fire at you.
- , p 166)