Magic

To use magic without a skill from some source, one of a character's two innate traits must usually be an Affinity.
Magic use can come in two forms: Spells and Skills.
Spells are the classic type of magic channeling, wizard style. To use a Spell requires feeding energy into intent. It takes full concentration and time, and can backfire or fail if done poorly. They can also harm the user if mishandled. Fire will still burn someone with no resistance.
Once a spell with a specific intent has been practiced enough, it can become a Skill.
Skills are not nearly as flexible as spells, as they are the solidification of the original intent and cannot variate. If the original intent was Fireball, the skill will always be a fireball, never a fire spear. But skills are immediate and cannot fail, backfire, or harm the user. In exchange for flexibility, the downsides have been removed as the spell becomes something controlled by the System.
Spells are meant to be more flexible, while being difficult to fit in. Practicing a Spell is considered actually practicing to gain a Skill of that spell, as Skills are always the preferred form despite the rigidity.