Colourful Indians
Atman means 'eternal self'. The atman refers to the real self beyond ego or false self. It is often referred to as 'spirit' or 'soul' and indicates our true self or essence which underlies our existence. The soul is immortality.
The atman becomes involved in the process of becoming and transmigrating through cycles of birth and death because of ignorance of its own true nature. The spiritual path consists of self-realization – a process in which one acquires the knowledge of the self (brahma-jñanam) and through this knowledge applied through meditation and realization one then returns to the Source which is Brahman.
When the Aatma becomes embodied it is called birth, when the Aatma leaves a body it is called death. The Aatma transmigrates from one body to another body based on karmic[performed deeds] reactions.