What is karma?
According to a living Avatar, Paramahamsa Nithyananda (fondly known as Swamiji), he said that Karma is anything which is left inside us incomplete, asking us for attention, for completion, and forcing us to go through that again and again. He also added that karma is nothing but the incomplete patterns brought from previous births as well as the new patterns accumulated from this birth.
Basically, there are three kinds of karmas. First, the Prarabdha is the karmas you brought with you to exhaust in this life. Second is Agamya which is the karmas you accumulated in this life. Lastly, Sanchita is the karmas you have saved for janmas (lifetimes). You cannot do anything with Sanchita karma, Sanchita can be melted or burnt only by an enlightened master or Guru working directly on it. You can work on first 2 karmas: Agamya and Prarabdha. Prarabdha karma is more like thoughts, engrams and patterns. Agamya karma is more like muscle-memory and bio-memory, which have become a part of you. Agamya karma itself has two parts – one is doing the actions in unawareness which bring suffering, and second is the pattern of doing such actions continuously and accumulating more Agamya, knowing it brings suffering.