In the realm of Warlocks, Earth is much like we see today, except that magic is an everpresent part of life. Cars run on gasoline as much as they do on magic, and fantastic elements supplement our modern amenities.
Not all humans use magic; in fact, most don't. Everyone is born with an aura, but most humans' auras are negligibly small. And even for those blessed with magical ability, many choose to pursue unrelated careers, and learn few spells, if any. Despite the scarcity, however, mage schools exist all over for those who want to study spellcasting, and even if you have a poor aura, there are always careers available in artificery, for those who are studious enough to seek them.
Mages theorize about a realm beyond their own--a plane of existence from which magic was born. Many seek out the power of such a realm, many dismiss it as nonsense, and many are trying to keep it a secret.