Character optimization (aka CharOp, Char-Op) is the process of crafting a game character using the rules to make them excel at some given role. Includes "practical CharOp", which is optimization that you might actually use in a game, and "theoretical CharOp."
While practical CharOp, solving specific build problems for a specific character in a specific game is encouraged here at RPG.SE, general theoretical optimization questions tend to be broad guessing games seeking things like "the best DPR." and usually are more suited to forum discussions.
Character optimization does not necessarily require being the "best possible build" at dealing damage or killing things, Instead, these questions can focus on any aspect of the character "made better" to some degree.
A completely valid question could be: "How can [this specific character] not die so much?" Another valid question is "My party [Made of this type of character, and this other type and this third type] is doing more damage than I am. Here's my build and the books we're using, how can I keep up with them?"
The essence of good optimization is finding and articulating intentions as accurately as possible. Stating the objective clearly with the parameters of the problem (disallowed books and combos) allows a good, correct answer to be found. Vague "I want to be better" while optimization, does not permit a good answer.
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The goal of Optimization is to make the best character possible. What makes the best character possible however, will often be defined by your group rules.