The Weave

The Weave is considered to be many things: materiel energy, life force, ki. Many saw it as a "fabric" on which magic was "drawn", and damaging the fabric causes magic to go awry. Some textbooks have been know to deliberately falsify the nature of the Weave, in an attempt to limit the knowledge associated with spellcasting. In the years after the Spellplague, the term Weave also became a synonym of the use of magic.
Casting a spell is equivalent to telling the Weave to rearrange itself to create an effect.
The Weave is also theorised to be linked to fate, and a rare few individuals could supposedly manipulate such connection to alter the future to their advantage