On Golarion, spells are categorized based on the effects generated by the power. These specialized groups are called schools. Any power not tied to a school of magic is considered to be a universal spell, such as wish. There are eight schools of magic: Abjuration, Conjuration, Divination, Enchantment, Evocation, Illusion, Necromancy, and Transmutation.
A spell is always considered to be from its school, no matter where it comes from. Boost Trait, for example, is a Transmutation power, whether it's cast from Arcane Background (Cleric) or Arcane Background (Sorcerer). The GM may decide, however, that a caster's specific Trappings move the power into a different school for that caster (so a GM might rule that, while a typical barrier belongs to the Conjuration school, a purely magical barrier might be an Evocation spell instead).
Knowing the schools of magic and their effects can be instrumental in identifying magical traps, weapons, items, or auras surrounding an opponent.
Here are the various schools and the powers that belong to each. Note: these lists do not affect which powers an Arcane Background has access to. These lists simply identify which powers are associated to each particular school and the general focus of the school of magic.
Abjuration: This is the school of protective magic. It's used to prevent harm and suppress other spells. Arcane protection, banish, deflection, dispel, environmental protection, protection, sanctuary.
Conjuration: This school focuses on altering reality by creating, restoring or moving objects and creatures. Barrier, conjure item, damage field, healing, planar binding, plane shift, relief, resurrection, summon ally, teleport.
Divination: This school focuses on predicting the future and learning the secrets held by others. Detect arcana, divination, locate, mind link, mind reading, object reading, scrying, speak language.
Enchantment: This school affects the minds of others, influencing or controlling their behavior. Beast friend, confusion, empathy, mind wipe, puppet, slumber.
Evocation: Evocation magic taps into the unseen source of power to produce spectacular effects. Blast, bolt, burst, havoc, light/darkness, stun.
Illusion: This school deceives the senses or minds of others. These spells often cause people to see things that are not there, or not see things that are. Conceal arcana, disguise, illusion, invisibility, sound/silence.
Necromancy: This school manipulates the power of death, unlife, and the life force. Blind, curse, drain Power Points, fear, lower Trait, zombie.
Transmutation: Transmutation changes the properties of some creature, thing, or condition. Baleful polymorph, boost Trait, burrow, darksight, elemental manipulation, entangle, farsight, fly, growth/shrink, intangibility, shape change, sloth/speed, smite, telekinesis, time stop, wall walker, warrior’s gift.