CharOp
CharOp is the abbreviation commonly used to refer to the Character Optimisation board on Wizards of the Coast's official forums. It is where players of WotC's games, usually Dungeons & Dragons of variable edition, unite in order to try and break the fuck out of the system any way they can. CharOp is responsible for finding most of the exploitable loopholes and badly-thought-through features in D&D, creating character builds such as Pun-Pun, designing infinite feedback loops that make people infinitely good at something, and otherwise stacking bonuses in unexpected ways to break the game utterly. The only purpose of discourse is to make the best character possible; having a given concept actually make sense is mostly irrelevant, so a charop player would gladly use a half-orc wizard or halfing fighter even though it doesn't make sense in the system, if there were any loophole that would allow for it to be effective.
Before we can go any further in discussing CharOp, we need to narrow things down, and provide some motivation.
Past this point, we'll just talk about optimization in 4e. Explaining Pun-Pun, for example, necessitates discussing snippets of rules from a dozen or more books, and this is certainly an optimized character for Dungeons and Dragons, where characters must deal with game-bending effects and situations too wild to list here. Thus, the thought processes there are completely different than what one sees in 4e, where very little can affect characters--you cannot even take away their hand weapons in this game, and even the 'rust monster' of 4e doesn't really destroy magic items.
Primarily, the only thing you can do to a character is hit point damage, so an optimal character might be concerned about having hit points. Unfortunately, the RAW ('Rules as Written', the only thing an optimizer can use to make judgements) for monster damage is so pathetically low, the healing so pathetically high, that this isn't much of a consideration.
Similarly, characters primarily, almost exclusively, defeat monsters by dealing hit point damage. The other two methods, exploiting flaws in saves--broken and recently fixed by WoTC--and abuse of the Intimidate rules--broken and likely fixed at some point by WoTC, are too easily exploited to necessitate any lengthy discussion.
The primary way characters do damage is by hitting. And this leads to our fundamental philosophy of optimization in 4e: +1 to hit is everything. 4e is an extraordinarly narrow game, there's really nothing else that's relevant. All of a character's powers are keyed off scoring hits. If you can't hit, your powers are worthless (again, there is an exception, in the form of the 'pacifist cleric', but let's focus on the other possible characters, some 99.9% of the possiblities).
How bad is it? WoTC created a feat, "Weapon Expertise", that grants, just that, a +1 to hit at low levels (more at high levels, but that's besides the point). This feat, this simple +1 to hit, is so dominatingly powerful that it's considered a 'feat tax', as all characters, even non-optimized ones, [i]must[/i] take this feat.