It is interesting to note that in Hindu religion, we talk of Samadhi. The meditation is done to achieve the Samadhi and ordinarily we talk of Samadhi -some one took Samadhi at age so and so. Sometimes it's called LIVE SAMADHI and sometimes when some great spiritual person dies we called it Samadhi too. But in real sense the Samadhi is a state which is achieved ultimately with the instruments that re given to us ,namely Mind , Intellect etc.
In Patanjali Sutra Yoga , the samadhi is divided in to 2 main types ,ASMAPRADYANT AND SAMPRDYANT . In a way one leads to other . ASAMPRADYANT SAMADHI happens when one has perfected SAMPRDYANT. The SAMPRADYANT SAMADHI is related to the instruments that are given to us by Nature or PRAKRUTI . The SAMPRADYANT samadhi is divided in to 4 stages . Each stage is going deeper and deeper and then when the last or the 4th stage is achieved , it leads to ASAMPRADYANT SAMADHI. The SAMPRADYANT SAMADHI creates impressions or SAUNSKAR and so some people call it CONSCIUS SAMADHI. The ASMAPRADYAT is sometimes then referred to UNCONSCIOUS SAMADHI.
This all may sound confusing . So let me try to make it simple
When the meditation is started ,we have it at the level of MIND and so we have lots of doubts and so this is at the lowest level and is called SAVITARK SAMADHI. Then when we go deeper in to it we are at the level of INTELLECT and we have some ideas or thought and so it is called SAVICHAR -VICHAR is thoughts. Then we go beyond and now we are at the level of CHITTA and we experience some happiness though transient and so it is called SANAND -ANAND is bliss or happiness . When one has experienced bliss linger and we go deeper then in ego or 'I'nes it is called SASMIT- ASMITA is ego or self awareness. In all these 4 stages we are AWARE of ourselves and so these stages are part of SAMPRDYANT SAMADHI .
The impressions that are created by theses stages lead finally to the highest level , where we have dissolved MIND -INTELLECT - CHITTA AND EGO OR AHANKAR OR SELF AWARENESS and that is called ASMAPRADYANT SAMADHI - Here we are not aware of separation of our physical body mind intellect and CHITTA - all that is part of PRAKRUTI and we are one with the PURUSH or SPIRIT.