All Skills that are not Physical, Gun, or in one case Hunt elements are usually considered Magic.
Magic as a StatEdit
Magic is one of the five recurring stats in the series, along with Strength, Vitality, Agility, and Luck, and typically affects Maximum Magnetite (or the equivalent measure for MP), the strength of spells, and resistance to damage from magic attacks.
Usage of Magic by HumansEdit
Humans in Strange Journey are unable to cast magic, though Guns created on the Red Sprite with Forma are capable of reproducing magic-like effects. Just as in Digital Devil Saga, human characters have a Null Light attribute, though this can be altered on the main character depending on what armor is equipped. However, as an inherent trait, this resistance will only change if an armor specifically affects it; most armors, whatever their resistances, will retain the Null Light attribute.
Raidou is unable to learn any skills that can be cast (example: Agi), though he is capable of combination attacks with some demons. In addition, Raidou is capable of using Magnetite for special attacks without the use of a demon, though he is unable to strike for elemental damage unless his weapon has been charged by a demon's skill.
Spells used by humans in the Persona series are activated by calling the Persona, though the exact method of calling the Persona varies by game.
Humans in Digital Devil Saga are incapable of using magic by themselves, though they can charge their weapons with various skills by performing a combination attack with a character who has transformed into their Atma Avatar. While active skills, such as attack spells, cannot be accessed while in human form, passive skills remain in effect. In addition, human form has an inherent Null Light attribute.
Humans in Devil Survivor and Devil Survivor 2 are able to use magic through their COMP. They are able to obtain more spells by learning them from defeated demons in battle, and may freely change what skills they have equipped outside of battle.
Use of Magic by DemonsEdit
Demons in Shin Megami Tensei have minimal alteration throughout the games; though their attributes (level, resistances, known skills, etc.) may vary widely by what game is played, by far the most common format is that enemies have a set list of skills that they will occasionally use, and recruitable demons will learn more skills as they level-up upon becoming allies. In addition, most demon Fusions will transfer one or more skills to the new demon, allowing them to learn skills (within certain limits) that they otherwise couldn't.
Enemies again follow the standard format, but allies do not gain additional skills as they level-up, instead providing the Main Character with various items that can be used in Demon Fusion to teach their skills to another demon.
While enemies follow the primary format for the series, Atma Avatars in Digital Devil Saga have the most customizable skillsets of any playable characters, being not only able to learn a wide variety of skills (any character can know any learnable skill except for a very small number of exclusive abilities), but retain knowledge of them even when they are replaced by another skill.