Karma is simply a word describing "cause and effect".
This is always operating.
Every choice we make (cause) creates or destroys or changes energy patterns,
resulting in an effect.
Each action,
emotion, each
thought,
radiates from us a frequency or vibration which will either
harmonize with or conflict with other frequencies we or others generate.
We automatically attract to ourselves the frequencies we vibrate / radiate.
We automatically attract to ourselves what we either pull to us or push away from us.
The only thing real about the virtual reality we call the physical world, is the impact we have upon each other, and that impact is either hurtful or loving. Giving love creates a karma of love, that love will be attracted to you. Giving hurt creates a karma of hurt, that hurt will be attracted to you. Unless we are completely neutral, we create karma... cause and effect. Karma is always being created unless we walk the planet in neutrality in the eternal now moment. The next level is unconditional love.
Hurt is always created by ourselves for ourselves when we are or do inappropriately for ourselves. When we don't know, we may ignorantly create hurt. This may be accompanied by pain and / or suffering.
Whenever we cause hurt in another by leading them astray from their appropriateness, we hurt them. It is in that case our own choice which is the cause of the karma, the effect of which is that they got hurt. Our karma is to be fully conscious of our causes and effects and to neutralize them in order to set our future free of the karma of our past.
We have absolute sovereignty... free will dominion... freedom to use our choice to create anything we choose, but / and doing so in a way which impacts upon others, will produce a karma, a linkage, a quantum entanglement, a connection between us. If that impact / effect is hurtful, then the environment in which we live will be damaged... we will be living with hurt, damaged, wounded, unhappy, miserble, suffering people, and we will likely not enjoy their company. With billions of us on this planet, we could run from our karma a whole lifetime... hurt one person and move onto the next. But the impact of that hurt will remain, and ultimately affect us.
True freedom combined with true power is what we seek. It exists and is available to us as individuals, not dependent upon any other. We may translate that as "the scalar vector field" of the "aether".
The definition of harm is that another's sovereignty was violated... that they experienced an affect chosen by another, which was inappropriate for them. Appropriateness is known in the heart chakra (thymus gland for physicists). Thus when we cause another to not follow their "heart's guidance", we harm them, create karmic bonds with them, create karma to heal, a lesson to learn, and are more deeply caught in this dimension.
An aspect of freedom is being able to leave this school, and that requires nuetrality and a completion of all karma. Since Ea-Rth has passed a fork in the road, and since all [mankind] on Gaia are passing the same fork in the road, we may wish to complete all our karma before the closure of the window of opportunity for [a]scension.
Beleif creates reality, so if we beleive something strongly enough, we may manifest our own little bubble of reality wherein we may harm others without consequences, but it takes a lot of energy to maintain that, contrary to the collective beliefs.
As we learn to operate in higher realms, we may obtain access to the causal plane, where we may in consciousness view and alter causal links, thus exacerbating or healing karma.