The astral plane, as with all planes in the multi-dimensional continuum of the universe, are density degrees of the universe. They are therefore fundamental to the creation of everything that exsits, has ever exsisted, and will ever exsist in the physical world. This is the origin of the term, "As above, so below". Everything exsisting in the material world must exsist first in the astral world.
The astral plane is also a reflection of everything that has ever occured in the material world, is occuring now, and will ever occur in the future, again is accordance with "As above, so below, as below, so above". (The "future" being realtive to the temporal concepts of the measurment of time as percieved within the three dimensions of the physical world.)
This plane is also the sphere of vibrations in which light, sound, colour, rhythm, and this all life and everything ever created, and will ever be created, has its origin. The astral worlds are therefore an emanation of the Eternal without beginning or end, and are therefore timeless, spaceless, and infinite.
The astral planes are home to a very wide variety of inhabitants in addition to humans. There are many beings and intelligences that have never incarnated on Earth, and whose task it is to assist in the evolution of mankind on Earth. There are also the beings of the single elements, many of which form the basis of earthly “faerie stories”. There are also the more simple beings of the elements known as “elementals” which are much less advanced, but nevertheless do exhibit a degree of intelligence and have their role to play in the grand Universal scheme.
Also living within, or visiting the Astral Planes are a very wide variety of beings of all levels and intelligences, most of which are beyond the comprehension of earthly man, including beings originating from other planets in the Universe.
In the Astral worlds there are many degrees of Energy, of vibration at which life exists, everyone and everything existing at a particular degree of vibration exhibiting similar characteristics.
In the mid-astral worlds or mid astral plane, at the level of vibration where most decent people currently find themselves after physical death, existence is one of peace, harmony and tranquillity, often in very stark contrast to the previous existence within the physical world of the Earth life system. These astral worlds also seem much lighter, solid and “real” than the physical world, which by comparison seems to be a very dull, murky, oppressive place indeed.
( I have included a version of the "death" process, in the views of someone who deals heavily with all things astral, and offers just one of the many possibilites that could happen when an individual dies)
There are many levels of vibration and comparative density of the Astral worlds, all of which exhibit their own unique Energy. A human being, indeed any being will after physical death automatically transition to the most appropriate Astral world, most closely matching his or her own particular vibration, ego, temperament, character, and most importantly the beliefs and attitudes of the person at the time of physical “death”. If a person is open-Minded and fully understands the process erroneously known as “death”, and assuming their previous life has been a normal and decent one, they will effortlessly transition to the light, peace and harmony of the mid-Astral worlds. More Spiritually advanced people will transition to the inner Astral worlds where conditions are even more blissful and beyond the comprehension of most people still living in the physical world of matter.
The entire Universe from the The Prime Creator, The First Cause, God is a continuum, consisting of vibration, Energy, from the very highest level of The Source down to the very lowest of the physical world of matter. All Astral planes form an integral, lower aspect of this vast and infinite Energy continuum.