A world-soul is the primordial life force of a world that has the potential to become a titan.[1] Existing titans sought out world-souls to protect and nurture them in hopes they could become another titan. The void lords also sought out world-souls in hopes of corrupting them and create a powerful void entity.[2]
Proto-titans[]
The world of Azeroth was identified by Aggramar of the Pantheon as having a promising world-soul and thus a very strong candidate to become a titan[3] which appeared to be confirmed later when it spoke to a recovered Magni Bronzebeard.[4]