All the Hindu & Buddhist religion is replete with rebirth stories. As per the philosophy of both the religions, soul of an individual being travels at death from one body to the other. In the case of Lord Buddha, he was able to see all his previous births with vivid clarity. Many Yogis & persons advanced in meditation can also see all their previous lives vividly. So can you if you are also advanced in meditation. As per Lord Buddha an individual soul goes through innumerable births & you have been in different bodies in your past lives before you were born this time. As per him this continuum of births was so lengthy that it did not make sense to see exactly where the process began. In the case of Lord Buddha, he acquired two sorts of insights, the ability to recall with visual clarity his previous lives & the ability to do so in the case of others too. All the previous lives of Lord Buddha are recorded as "Jataka Stories".
Jataka Stories have been an integral part of Buddhist culture through the ages. ‘Jataka Stories’ are a collection of tales about Gautama Buddha’s previous births as a "Bodhisatva". Collections of Buddhist legends compiled at various dates in several countries; the oldest and most complete has 547 stories. So there are 547 recorded past lives stories of Lord Buddha. They were collected before AD 400. They give an account of previous incarnations of the Buddha. The various "Bodhisattva births" (earlier births of Lord Buddha) portrayed in the Jataka stories range from gods to fairies, to kings, Brahmins, merchants, craftsmen, potters, slaves and outcastes, to animals, birds, and fish. So as per Lord Buddha he was in his previous many births, not only in human bodies but also took birth as birds & animals. Hindu religion also talks about 8.4 Million different types of species in this universe & a soul goes from one type of body to the other as per the Karmic law.
Below are few verses of Bhagwat Gita which explain about the rebirth:
"dehino-asmin yatha dehe
kaumaram yauvnam jara
adhiras tatra na muhyati" (Bhagwat Gita: Chapter Two verse 13)
"Sri Krishna said: Just as boyhood, youth & old age are attributed to the soul & the embodied soul continuously passes through these cycles, similarly the embodied soul passes into another body at death. The wise man does not get deluded & bewildered with such a change."
"vasamsi jirnani yatha vihaya
navani grhnati naro ’parani
tatha sarirani vihaya jirnany
anyani samyati navani dehi" (Bhagwat Gita: Chapter Two verse 22)
"Sri Krishna said: As a human being puts on new garments, giving up old ones, the soul similarly accepts new material bodies, giving up the old and useless ones."
"jatasya hi dhruvo mrityur
dhruvam janma mrtasya cha
tasmad apariharye ’rthe
na tvam socitum arhasi" (Bhagwat Gita: Chapter Two verse 27)
"Sri Krishna said: One who has taken his birth is sure to die, and after death one is sure to take birth again. Therefore, in the unavoidable discharge of your duty, you should not lament."
bahuni me vyatitani
janmani tava charjuna
tany aham veda sarvani
na tvam vettha parantapa" (Bhagwat Gita: Chapter Four verse 5)
"Sri Krishna said: Both you and I have passed through many, many births. I can remember all of them, but you cannot, O winner of the enemy!"
Sometimes it happens in our life that some unknown out of the crowd seems so known to you, though you have met that person for the first time. If we meet someone & form meaningful close relationship with that person, then the assumption is that we may have previously met & have associated with that person in previous births also. As a Karmic connection we meet that person again & maintain connections in this lifetime also. Same is the case with all the persons who are close to us in this life. It is not just like that we have suddenly become so close to those people. It is only that all these people were in our lives in our previous births also. We are together here because we had been together before in our previous lives.
In Hindu scriptures Karma is related to the origin of one's own body. Karmas of earlier birth become the basis of this birth & Karmas of this birth become the basis of your next birth & so on. At death, soul of a person takes the stock of all Karmas (having its reservoir in that person's mind) & Divinity or God as per the divine law takes a handful of those Karmas & a new body is made with the seeds of these Karmas. So if a person has done good Karmas he/she gets a good godly body in heavens & if he/she has done bad karmas in this life then that person's soul goes to lower wombs of birds & animals. So it is generally said that we should do good Karmas only.
Below are few verses of Bhagwat Gita which explain about how a soul travels from one body to the other & where it goes as per the Karmic law:
"sariram yad avapnoti
yac chapy utkramatishvarah
vayur gandhan ivasayat" (Bhagwat Gita: Chapter Fifteen verse 8)
"Sri Krishna said: O Arjuna, As the wind carries away odours from their seat, even so the Jivatma (soul), the lord of the body, snatching these (the mind & the senses) from the body, which it casts off, migrates into the body, which it acquires.
"yada sattve pravrddhe tu
pralayam yati deha-bhrt
amalan pratipadyate" (Bhagwat Gita: Chapter Fourteen verse 14)
"Sri Krishna said: O Arjuna, When one dies in the mode of goodness, he attains to the pure higher planets of the great sages."
"rajasi pralayam gatva
tatha pralinas tamasi
mudha-yonisu jayate" (Bhagwat Gita: Chapter Fourteen verse 15)
"Sri Krishna said: O Arjuna, When one dies in the mode of passion, he takes birth among those engaged in fruit producing activities (i.e. as a man or woman on earth); and when one dies in the mode of ignorance, he takes birth in the bird & animal kingdom."
As per the Hindu Philosophy, any "Karma" done by a person, remains with that person, unless he/she has enjoyed the consequential Fruit arisen out of doing that Karma. For a good act done by him, he shall bear good result & enjoy it. Similarly for a bad act done by him, he shall bear bad result & shall have to bear punishment for it. So ,whatever, action/karma we perform with our body, mind or even speech, it should not do harm to others but should be of some use only to others. By doing good Karmas only we shall get good life in future births & shall finally meet the God.
Read also...............Understanding "Karma" as per the Hindu Philosophy?
Read also...............Is there Life after death?