You know some thing about astral projection?

yeah... i've done it once accidentally...i see my body lying in my bed, i feel like floating..

Like islander7 outlined, it is a tool you can employ to travel to the astral planes. Expanding on that, it is a tool in which you can travel to the astral plains for: learning, fun, growth, or, simply, relaxation. The first few times people do it consciously or with the aid of substances or emergency they typically only do it for a few seconds as they first become very enthralled with the feelings and then get scared which immediately returns them to their perceived safe haven - aka their body. Returning to the body is akin to getting out of a pool - for those unfamiliar with the concept and for the point of illustration. After being free to do whatever, wherever, going back into the heavy, slow meat clothing is interesting. Additionally, most people astral project every night - aka the dream world. Many people do not recognize their ability to control their dream or this state and just float through passively. Anyone who has "woken up" while inside the dream, changed their dream while "sleeping", or felt like they were flying were already projecting naturally.

nope

no...i donno...1st time i am hearing about...astral projection