What is good karma? What is bad karma? Who defines it?

Good and Bad karma:

Good karma is bound when we have intention to make others happy.Bad Karma is bound when we have intention to hurt others.
Why did I highlight the word “intention?” It’s because Karmas are bound mainly through intent. It is the inner intent that causes the bondage of karmas. Actions are effects and intents are causes. Therefore, one has to be careful of one’s intention so as not to spoil it as that will become a bad karma in next life! Let’s understand this through an example.

There was a wealthy businessman who donated 25 lakh rupees to a charity. One of his friend asked him, “Why did you do this?” The businessman replied, “I would not have donated a single paisa had it not been the pressure of the Mayor.”

So what do we infer from the above example?
The donation he made is a visible karma, the rewards of which he will get in this life. People will praise him for his generosity.

But while donating, he made the intent, “I would not give even a single paisa.” This is a subtle karma, which is the cause for the next life’s effect. Since the intent is not for good of others, it is a bad karma.

As a result, in next life, he will not be able to donate a single paisa and that will make him very uneasy and uncomfortable!

This is how one binds bad Karma. So, we must always be careful not to spoil our intent because that will bind Demerit Karmas and bring lot of unhappiness inside.
Now, at the same charity where the wealthy businessman donated his money, there was a poor man who was asked to make a contribution. This poor man was very sincere and heartily. He had only 50 rupees, so he gave all 50 rupees in charity and let the staff know that “I have only this much money. I would have donated one crore money without any hesitation if I had the money.”

What kind of karma does this poor man bind? Let’s see...
The 50 rupees donation is the poor man’s visible karma. His sincerity and heartily nature touches the staff. The poor man, with the intent, that “I will give one crore rupees without hesitation to charity” binds good subtle karma.

As a result, in next life, he will be a very wealthy person and will be able to donate one crore rupees with lot of peace and happiness.This is because of ripening of Merit karma (Good Karmas). When the intent is that of not hurting others and moreover doing well for others, we bind good Karma which bring peace and happiness.

To conclude, if the motive behind an action is bad it will bind bad Karma. These bad karma bring unhappiness. And if there is a good intent within, you bind good karma. Such karma bring happiness. Therefore, let’s make a strong intent today that, “May I hurt no living being through my thoughts, speech or action.” We can even repeat this intent 5 times every morning, it will help us in a great manner.

Every person keeps binding good and bad Karma in life.
However, both these karma are like shackles - good karma is made of gold whereas bad karma is made of iron. And until one continues to bind karma, one cannot be liberated from the cycle of birth and death. Only when one attains Self-Realization, one is able to break-free from this vicious cycle.

https://www.dadabhagwan.org/self-realization/ is a good resource for those who would like to know more about how to attai
Self-Realization.