The Weave

The weave is much like the concept of laylines but on a much, much smaller scale. Rather than immense lines spanning not much space each line in the weave is just a single gossamer thread in a tightly woven blanket wrapped around every plane known. Magic lies completely unnoticed and unseen until vibrations run along it like the plucking of a guitar string. The weave is also bizarrely moody and not always terribly sensible which makes pioneering new magics a very difficult thing. 
Learning to interact with the weave is how one learns to cast magic, most especially wizards. Inherently magical beings seem to interact with the weave just by existing, their souls or bodies moving it in specific patterns or even simply bunching it around them. This ethereal presence seems to be tied to the concept of auras, perhaps the closest connection one can find between psionics and magic.

Dead Magic Zones

Dead Magic Zones are places where the weave has been ripped apart so thoroughly that there is nothing to pluck when casting magic. This would typically involve a severe magic expenditure all at once, like friction wearing holes in an outfit but at intense speed. The weave tends to recover naturally but it is possible to damage large areas beyond repair if ripped too far apart. Without decades of tending and tugging the frayed edges of the zone by someone with intimate knowledge of and feel for the weave it will permanently remain a dead magic zone.
Some spells create temporary dead magic zones through selective repulsion rather than wearing anything away.This can include dispelling effects or anti-magic enchantments and fields, but it can be more reactive instead resisting things like being seen through divination.