One of the basic beliefs of Hinduism is the law of Karma or Action. It basically means that every good thought, word or deed begets a similar reaction which affects our next lives and every unkind thought or evil deed comes back to harm us in this life or the next. There are three stages of Karma:
Prarabdha Karma: According to this, the body or tenement the soul chooses to be born in is not under human control and depends on the sum-total of favourable and unfavourable acts performed in a previous life. So also the time of death. If your time on earth is not over, you cannot die no matter what happens, but when your time comes near nothing can save you.
Samchita Karma: This is the accumulated Karma of previous births which gives us our characteristics, aptitudes, etc. This is changeable and man can improve his habits, get rid of evil thoughts and desires while a good man can fall on evil ways.
Agami Karma: This Karma consists of actions in our present life which determine our future in this life as well as in the next.
The best or ideal Karma is the one which is performed as a point of duty towards God or mankind without seeking any rewards (Nishkama Karma).