Prarabdha-karma
Prarabdha Karma are the part of sanchita karma, a collection of past karmas, which are ready to be experienced through the present body (incarnation).
According to Sri Swami Sivananda: "Prarabdha is that portion of the past karma which is responsible for the present body. That portion of the sanchita karma which influences human life in the present incarnation is called prarabdha. It is ripe for reaping. It cannot be avoided or changed. It is only exhausted by being experienced. You pay your past debts. Prarabdha karma is that which has begun and is actually bearing fruit. It is selected out of the mass of the sanchita karma."
Each lifetime, a certain portion of the sanchita karma, most suited for the spiritual evolution at the time, is chosen to be worked out, during the course of the lifetime. Subsequently this Prarabdha Karma creates circumstances which we are destined to experience in our present lifetime, they also place certain limitations via our physical family, body or life circumstances we are born into, as charted in our birth chart or horoscope, collectively known as fate or destiny (determinism).