Astral Projection is the projection or travel of the mind into the astral planes. The astral planes are slivers located in each dimension. There are thousands of planes that range in levels, but not all are mental projection sites; no human being has ever even visited many planes and many cannot be visited by human beings at all. When the mind transcends to the astral planes the mind does not wander off per say, it is connected to a cord that is fixed to you mind by that which is best known as the "Silver Cord.” Another form known as astral projection is the projection of yourself in the physical to a remote or non-remote location, which can be seen by others or you just peek at what is going on without others being aware. 
1. Astral projection (or astral travel) is an esoteric interpretation of a type of out-of-body experience that assumes the existence of an "astral body" separate from the physical body and capable of traveling outside it. Astral projection is experienced as being "out of the body".
The idea of astral travel is rooted in common worldwide religious accounts of the afterlife  in which the soul's journey or "ascent" is described in such terms as "an...out-of body experience, wherein the spiritual traveller leaves the physical body and travels in his/her subtle body (or dreambody or astral body) into ‘higher’ realms."
There is little evidence for astral projection, and that which does exist rests mainly in subjective personal accounts of the experience. Hundreds of personal accounts of astral projection were published in a number of books through the 1960s and 70s in an effort to validate religious concepts of the soul and an afterlife. Because of their subjective nature, however, there are many plausible explanations that can account for these experiences which do not rely on the existence of paranormal, supernatural, or psychic activity.
Measurement and Observation
Astral projection, or astral travel, denotes the astral body or double leaving the physical body to travel in the astral plane. The astral body, in classical, mediaeval and renaissance Neoplatonist philosophy as well as that of the later Theosophists and Rosicrucians, is a body of light intermediate between, and uniting, the rational soul and the physical body, while the astral plane is a world of light, composed of the spheres of the planets and stars, likewise intermediate between heaven and the physical world. These astral spheres were held to be populated by gods, angels, demons and spirits. 
The idea of the astral figured prominently in the work of the ninteteenth-century French occultist Eliphas Levi, whence it was adopted by Theosophy and Golden Dawn magical society. The Theosophists also took note of similar ideas (Lin'ga S'ari-ra) found in ancient Hindu scriptures such as the YogaVashishta-Maharamayana of Valmiki.
However the expression came to be used in two different ways. Whereas for the classical and mediaeval philosophers astral "projection" was a journey to other worlds, such as heavens, hells, the astrological spheres and other imaginal landscapes - a meaning which it kept in the Golden Dawn and among some Theosophists - by others it was taken to mean travelling, in a ghostly form, around the ordinary physical world. It is this latter meaning, perhaps, though strictly it has nothing to do with the "astral", that is now most widely recognised.[improper synthesis?] Later Theosophists such as Leadbetter and Bailey designate this latter "etheric" travel.
The subtle bodies, and their associated planes of existence, form an essential part of the esoteric systems that deal with "astral" phemonena. In the neo-platonism of Plotinus, for example, the individual is a microcosm ("small world") of the universe (the macrocosm or "great world"). "The rational soul...is akin to the great Soul of the World" while "the material universe, like the body, is made as a faded image of the Intelligible". Each succeeding plane of manifestation is causal to the next, a world-view called emanationism; "from the One proceeds Intellect, from Intellect Soul, and from Soul - in its lower phase, or Nature - the material universe". Often these bodies and their corresponding planes of existence are depicted as a series of concentric circles or nested spheres, with a separate body for traversing each realm.
Concepts of "soul" travel also appear in various other religious traditions, for example ancient Egyptian teachings where the soul is presented as having the ability to hover outside the physical body in the ka, or subtle body. A common belief is that the subtle body is attached to the physical body by means of a psychic silver cord.
Belief that one has had an out-of-body experience, whether spoken of as "astral projection" or otherwise, is common. Surveys have reported percentages among respondents feeling that they have had such an experience at some time in their lives ranging from 8% to as much as 50% in certain groups.
Commonly in the astral projection experience, the experiencer describes themselves as being in a domain which often has no parallel to any physical setting, although they say they can visit different times and/or physical settings. Environments may be populated or unpopulated, artificial, natural or completely abstract and from beatific to horrific. A common belief is that one may access a compendium of mystical knowledge called the Akashic records. In many of these accounts, the experiencer correlates the astral world with the world of dreams. They report seeing dreamers enact dream scenarios on the astral plane, unaware of the more extensive and varied non-physical environment they feel surrounds them. Some also state that "falling" dreams are brought about by projection.
The astral environment is often theoretically divided into levels or planes. There are many different views concerning the overall structure of the astral planes in various traditions. These planes may include heavens and hells and other after-death spheres, transcendent environments or other less-easily characterized states.
In contrast to astral projection, in the etheric projection is described as the ability to move about in the material world in a etheric body which is usually, though not always, invisible to people who are presently "in their bodies." Robert Monroe describes this type of projection as a projection to "Locale I" or the "Here-Now", and describes it as containing people and places that he feels actually exist in the material world. Robert Bruce refers to a similar area as the "Real Time Zone" (RTZ) and describes it as the nonphysical, dimension-level closest to the physical.
According to Max Heindel, the etheric "double" serves as a medium between the astral and physical realms. In his system, the ether, also called prana, is the "vital force" that empowers the physical forms in order for that change to take place. Heindel says this means that when one views the physical during an OBE, they are not technically "in" the astral realm at all.
The subtle vehicle remains connected to the physical body during the separation by a so-called “silver cord”, said to be that mentioned in Ecclesiastes 12:6. Stephen LaBerge suggested in his 1985 book Lucid Dreaming that all such "out-of-body experiences" may represent partially lucid dreams or "misinterpreted dream experiences", in which the sleeper does not fully recognize the situation. "In the dark forest, one may experience a tree as a tiger, but it is still in fact only a tree."
Hugh G. Callaway, under the pseudonym Oliver Fox, published a series of articles in The Occult Review during the 1920s that later became the basis of a book, Astral Projection (1939). Hereward Carrington, a psychical researcher, along with Sylvan Muldoon, who professed ease with astral projection, published The Projection of the Astral Body in 1929. Both Callaway and Muldoon wrote of techniques they felt facilitated a projection into the astral. Among these practices included visualizing such mental images as flying or being in an elevator traveling upward, just before going to sleep. They also recommended trying to regain waking consciousness while in a dream state (lucid dreaming). This was done, they wrote, by habitually recognizing apparent incongruities in one's dream, such as noticing a different pattern of wallpaper in one's home. Such recognition, they said, sometimes resulted in normal consciousness, but with the feeling of being outside the physical body and able to look down on it.
In occult traditions, practices range from inducing trance states to the mental construction of a second body, called the Body of Light in Aleister Crowley's writings, through visualization and controlled breathing, followed by the transfer of consciousness to the secondary body by a mental act of will.