The preliminary instruction in the Bhagavad-gita is that one should know that the identity of the individual living entity is not lost even after the end of this present body, which is nothing but an outward dress only. As one changes an old garment, so the individual living being also changes his body, and this change of body is called death. Death is therefore a process of changing the body at the end of the duration of the present life. An intelligent person must be prepared for this and must try to have the best type of body in the next life. The best type of body is a spiritual body, which is obtained by those who go back to the kingdom of God or enter the realm of Brahman.

Srila Prabhupada; SB 2.1.15 purport