In astral projection the astral body leaves the physical. The astral body is one of seven sheath
bodies we all have - as we are all multi-dimensional. These bodies include the physical, mental, causal, etheric, emotional, spiritual.
What I have found is that some people can astral project naturally - and have been doing it for years. Other people are afraid to leave the physical body and struggle with it never being able to astral project. These people should try remote viewing as an alternative.
In astral projection you remain attached by a silver "umbilical type" cord to your physical body - though you may not see it. You travel out and are aware of things you encounter along the way.
To astral project, as with all out-of-body experiences one must feel totally relaxed, clothing fitting comfortable, reclining is best. Often a comforter is best over the body as the physical body sometimes gets cold when you travel out. You can practice alone or with one person. Find a quiet place . . . free of distractions. . . Adjust the lighting and room temperature. . . Adjust clothing . . . footwear . . . eyeglasses. Sit down or lie down . . . Find a position that is comfortable for you . . . Quiet your mind . . . Still your thoughts . . . Relax your body. . . Your face . . . your jaw . . . relaxing . . . Your shoulders . . . your neck . . . relaxed Your arms . . . your hands . . . feel at peace . . . Your torso . . . your hips . . . letting go . . . Your legs . . . your feet . . . totally relaxed . . . Focus on your breathing . . . Inhale slowly and deeply through your nose . . . Retain the breath as long as is comfortable . . . Exhale through the mouth slowly and completely . . . Repeat for two more breaths . . . or as is comfortable.
Let go of the fear of leaving your physical body. Remember you do it when you sleep.
See yourself floating away from your physical body. You may feel as release or perhaps hear a sound as you leave.