Today I'm going to talk about traits and edges. These may not be the same thing you are used to under these names, but there is no official RPG dictionary, and I've seen dozens of varying mechanics under these names in as many games, so I'll go with my own implementation.
In my games, Traits are attached to the character - they are part of the character's personality, and help define it. I implemented Traits for the first time in Blood Games II, as an optional mechanic, but they proved so useful that I've implemented them in every game I've written since then - this time as part of the core rulesets. Traits are created with the character in chargen. They can be made up by the player, or picked from a list of examples.
The player has 7 points to be distributed among at least three traits, with no one trait having more than 4 points. The more points a trait has, the more important that trait is to a character. Thus a character might be Lazy 3, Easy-going 2, and Patient 2; or maybe Off Kilter 2, Inspirational 2, Tactless 1 and Meticulous 1. Traits always add up to 7.
The first use of traits is thus to define a character's personality. that Lazy 3 character is going to be very lazy indeed, but also patient and easy-going almost as strongly. The traits add up to a quick word-picture that neatly describe and define that character's personality.
The second use of traits is as an expendable resource. When a player can justify an action to the GM - or possibly to the group, if you prefer - as being helpful to what he's trying to accomplish, the character can use those traits to help, as many as the player wants up to the number the character has. Each point is worth a bonus - depending on what the task resolution sub-system I'm using is, of course, the value of the bonus would differ. It might be worth an extra die per point in a dice pool game, or a 10% bonus in a percentile game, or a +1 to a roll-under game. These points refresh every session, so players tend to use them when something is important to them.
Edges are the result of something external to the character. I introduced Edges in In Harm's way: Wild Blue, and I'm also using them in On Her Majesty's Arcane Service. In Wild Blue, which is a game about modern mercenaries, certain training gives certain edges, so if a character went through - say - Military Police training, she'd gain the Edges Crowd Control 2 and Prisoner 2. In OHMAS, a game about magic and monsters in Elizabethan England, the Edges change every day, and are "discovered" - randomly rolled, that is - by a certain character type with Astrology skill. So one day Conflict might have an Edge in Flanking, and Reason might have an Edge of Deceit. The next day, Conflict might have an Edge in Brutality, while Reason has an Edge in Analysis. There are other categories of Edges, by the way, not just Conflict and Reason. I am just using those as examples. Which categories the PC is interested in that day are determined by the character.
Edges are always in effect so long as the condition holds true, and are not used up. Unlike Traits, Edges are not a depletable resource. So long as that ex-MP is dealing with prisoners, or crowd control, she has a bonus of two points. So long as the OHMAS party is using flanking in any conflict - of any type, not just combat - they have a 1 point bonus. Again, the value of those points varies from game to game.
So there you have it - my take on Traits and Edges.