Magic is inherent to the world of Tygris; magic is the very framework of life. All living beings have at least a spark of magic within them, that which makes them alive. Certain people and beings possess more than this drop of magic, and they are the mages.
Mage-power exists in two forms, called schools: conventional magic and craft magic. Being a mage does seem to run in families, but the talents of the children may differ from the parents, and it is certainly not unheard of for a mage to be born of two ordinary parents.
There are, very rarely, people and creatures which are born with an odd immunity to magic – they have the spark of life, but active magic does not work on them.