I figured that it was about time I start a thread.
There seems to be a lot of confusion on what negs and push-pulls are, as well as when and if they should be used.
A neg is a a backhanded complement, or a statement that could be interpreted as a low judgement call of the targets value.
A Push-Pull a neg, physical gesture, or other statement of disinterest followed relatively quickly by a complement, ioi, or positive qualifier.
An insult is a statement that is merely meant to anger or hurt the target.
Many people claim that negs serve no purpose in mature game. I tend to disagree, however many PUA's use them incorrectly. A neg should never be used to punish a woman, or for devastating her perceived value when she hasn't done anything to deserve it. A neg is useful when, for reasons outside of your control, the woman perceives you as of lower value than her. It can also be very useful in snapping a girl out of a b1tchy mood. From either position it is very hard to raise attraction. If she sees you as having lower value, you must spend large amounts of time trying to dhv yourself while not coming across as hitting on her. If she is in a b1tchy mood, you would have to attempt to dance around her attitude by disarming her extra sensitive b1tch shield, while attempting to not lose more value. These are excellent places to employ a neg. The neg is like an instant reality check. It lets the woman know, that you are playful, but you will not put up with their crap. If preformed correctly, it will instantly raise your value, and make her chase you. All negs should be said in a playful and generally joking manner. You are not trying to insult the girl. Another common misconception is that a neg should always lower the value of the girl. That is not true. If the girl is being b1tchy then a little harsher neg to knock her off her pedestal is probably warranted. Much of the time there is no need to lower the woman's value and it would even be detrimental. In this case, the neg should generally be a little lighter, and not as pointed towards her. The goal of this type of neg is to make her do a double take on her initial read of your value level by showing her that you have too much value to pander to her. There is a whole sticky thread devoted to specific negs if you want examples. I would personally never use many of them because I think they come off as amateurish, and potentially very insulting.
A Push-Pull is an more advanced evolution of the neg in many ways. In a push-pull the goal is to either jam the woman's b1tch-shield by sending mixed signals, or to complement her in a way that will build attraction without the fear of looking like an AFC. Push-pulls can be used at almost anytime during the interaction and will almost always build attraction if done carefully. The one caveat with a push-pull is that it isn't very effective if the woman perceives herself to be of much greater value then you. In that scenario, it looks like you either are trying to get back in her good graces (after the little neg like "push"), or your "pull" means nothing to her because of your low value. Therefore you should only employ it when your value is about the same level or higher than the woman you are gaming.
They have absolutely no place in gaming. In this group a put about 80% of so called "negs" which teeter dangerously close to being flat out insults.
Feel free to add to this definition, or state potential corrections.