Skill: Concentration
The Concentration is a relatively passive, but important skill for maintaining control of oneself, or pushing through certain ill effects. Concentration talents are often passive or allow for easier saves during certain situations.
Mechanically, a creature can only Concentrate⚙️ on one ability at a time, but must make a Concentration skill check whenever they take damage to maintain that skill, even if they are untrained in this skill. Concentration also provides passive ways to mitigate, or even completely ignore, nasty conditions for those who specialize in it, making it an entirely defensive skill.
Concentration only uses CON / Constitution by default. Concentration is a Primary Skill, meaning it is a major skill that can only be gained by mechanics that grant proficiency.
Skill Talents
These Talents can be gained during Character Progression or other means (such as gaining it from a Background, Increasing your Intelligence attribute, gaining the Expert Talent Gain Class Feature, etc).
Like all Skill Talents, these are meant to be good at anyCharacter Level they are obtained.