There are three types of karma – agamya, prarabdha and sanchita.
Sanchita karma is like a bank, a reserve bank. Understand, this may not be the first time you have taken a body and come to planet earth. You may have taken millions of bodies before! In those millions of bodies, whatever thoughts you had, whatever you spoke, whatever you did, all those unfulfilled experiences have become your engrams or engraved memories. Put together, they are like a bank called sanchita karma. When I say ‘bank’, it is not a collection or saving, it is debt! You will have to pay back all the loans!
The next type of karma is prarabdha karma. Prarabdha means, from the sanchita bank of karma you take some karma out of which you create your present body. You then decide to enjoy and exhaust all those karmas that you brought with you through that body. So prarabdha is just a small bit of the accumulated sanchita karma account that you have brought into this life. You have planned to enjoy or exhaust these through this body of yours.
The third type of karma is the worst. It is the agamya karma, the karma that you start collecting after coming down to planet earth, because of fresh thoughts, words and deeds.
Anybody who lands on planet earth has to exhaust his prarabdha karma before he dies. For example, let us say you have 1000 karmas in your sanchita bank. Out of these 1000 karmas, suppose you take only 10 karmas with you as your prarabdha karma when you take up your body saying, ‘Let me finish these 10 karmas this time.’ However, after coming down, instead of exhausting your own prarabdha karmas, you start watching others and collecting karma based on their desires. These are desires that you have borrowed from others around you. Because of these borrowed desires, you create certain thoughts, words and actions.
For example, if you see someone more beautiful than you, your thoughts multiply due to comparison and jealousy. You create karma based on thoughts. Sometimes you talk ill of others, without knowing any of the related facts. When you do this, you accumulate karma based on words.
source: Living Enlightenment