Reincarnation - Rebirth

Reincarnation is the concept of rebirth after the biological death of the living being. The concept is very popular in many religions including Sanatan, Buddhism and others. In Sanatan religion it is very much evident in Vedic scriptures. In Bhagwat Gita Lord Krishna explained the concept in great detail. 

It is well known that we keep changing our old and torn cloths. In the same way the living entity inside the body ( Soul ), changes its biological body once it becomes useless. The process keeps on going and the living entity takes a new physical body based on the deeds or the Karma.

With the Reincarnation only the body changes and not the living entity or the Soul inside the body. The concept has detailed explanation in Sanatan as well as in Buddhist philosophy.

In Sanatan philosophy what kind of body we will get in next reincarnation broadly depends on our present deeds with the present body. Only the Human being in this universe has been empowered with the wisdom and can act independently, while soul in animals, insects or in a plants act under human interference or by natural instincts. This is why the acts performed by the animals or plants neither punished nor rewarded.

Since Almighty God has empowered human being with the wisdom, the acts performed by human beings are very much rewarded in either senses ( good or bad). For the sake of mankind, while preaching Arjun , Lord Krishna explained in detail what kind of body one gets in rebirth.

In simple words it can be expressed as an equation of Good and Bad deeds. 

If the good deeds equal bad deeds, one is born as an ordinary human being.

If good deeds exceed bad deeds, one is born as an intellectual & prosperous human being.

If bad deeds exceed good deeds, one is born as an animal, a bird or insect etc. based on the severity of the bad deeds.

The goodness of the deeds doesn't imply simply to acts rather it is collection of thought, word, and act referred to as मनसा , वाचा , कर्मणा in Sanatan scriptures.

Soul being energy tied with eternal source of Energy ( God ) , easily adjusts and adapts to the new body whether human, animal or plant. The journey of the soul for the body starts from the conception and ends with the death of the biological body.

In Sanatan scriptures it has also been explained in great detail what and who will be our relations, friends, enemies etc. We can refer to Sanatan scriptures like Garud Puran, Upanishads if we wish to understand the complete journey of the soul.