There are so many types of Karma, there is individual karma, family karma, society karma, karma of the nation, karma of time.
Then there are karmas which are Sanchita, i.e., karma which have been accumulated; and Prarabdha karma, which are already giving fruits. Then there is Aagami karma, which is going to come in the future.
So it's very complex, almost like how food gets digested. When you take food in the mouth, first the saliva digests the food, a lot of the starch in the food is digested by the saliva. Then it goes to the stomach, and the stomach juices digests it further. Then it passes through the duodenum, and the pancreas.
You know, if you look into the mechanics of how a piece of banana gets digested, it is a huge factory! It is a huge factory to make a piece of banana, or apple to a drop of blood. And that's what our body does effortlessly.
Similarly karma is enormous. That is why Krishna says in the Bhagvad Gita, 'Gahana karmano gatih'. It means, unfathomable are the ways of karma. So the best thing is, don't sit and worry about karma, just do what is in front of you, and be spontaneous.
Clear head, pure heart and spontaneity in action, this is the sutra (rule) we must follow. We must have a clean heart, a clear mind and spontaneity in our action, and this will take care of all the karmas.
Bad karmas will go away when you do meditation, when you become hollow and empty. When you meditate, when your intentions are clear, then many of the bad karmas get dissolved. So, this is what it is. Knowledge, awareness, seva, satsang, sadhana – all these help in dissolving bad karmas.