Good

Overview
Understanding or agreeing on what is good (as well as what is bad) is obviously necessary in order to be able to evaluate the overall good or bad, or net good, of a particular decision.

Related Terms

 * Best: better than any of the alternatives.
 * Better: either:
 * containing more of some particular good...
 * containing more net good...
 * ...than one or more alternatives

Speculation
It may be enlightening to examine what types of things we, as humans, find to be positive or negative on various levels:
 * things to which we react positively on a visceral level
 * things which any rational person would agree are undeniably good

Most things held to be "good" seem to be quasi-circularly defined, e.g. "being good to someone" is generally good itself, as long as that other person isn't being bad in particular ways, but what is "being good to"? It may be that "good" can be almost entirely defined as "helping each other to avoid badness" or "...to avoid bad things from happening", where there is certainly a long list of avoidable bad things.

"Good" would also certainly include actions which aided work towards improvement of some sort. There may, however, be near-complete disagreement about what would constitute "improvement" or even whether any kind of overall improvement in the human condition is even possible (without an overall improvement, you have a zero-sum game and the best you can hope for is to minimize bad things locally).

List of undeniably good things

 * Helping other people (unless such help would harm others)
 * Being willing to help other people (which can also be viewed as "caring about other people", a superset of the non-erotic type of "love")
 * Working hard (at something good or at least non-bad) without drawing undue attention to one's efforts
 * Asimov's Three Laws of Robotics, taken as instructions to a person rather than a robot, would certainly be called "good" behavior, although most people would not be practically able to live their lives entirely by these rules:
 * ("A robot may not harm a human being, or, through inaction, allow a human being to come to harm.") You may not harm another person or, through inaction, allow another person to come to harm.
 * ("A robot must obey the orders given to it by human beings except where such orders would conflict with the First Law.") You must do what other people tell you to do, unless doing so would conflict with the first law.
 * ("A robot must protect its own existence, as long as such protection does not conflict with the First or Second Law.") You must protect your own existence, unless doing so would conflict with the first or second laws.

List of viscerally appealing things
These things appeal to most people's sense of "good", and probably are good most of the time although they can still be used to bad ends:
 * Loyalty (especially personal loyalty, or loyalty to one's family)
 * Friendliness, openness

Even though these things can be abused, they probably represent features we'd like to encounter frequently in an ideal world, and so may be innately good in some way.