2.  Sometimes called “ESP,” the psychic ability to perceive things invisible to most people, such as auras, various health indicators, spirits, as well as things at a distance in space or time. It includes skrying.

Both clairaudience and clairvoyance, and other psychic skills, have been induced through hypnosis and self-hypnosis showing them to be innate to the human psyche.

"As part of the unfoldment of the human intellect into omniscience, the development occurs at a certain stage of human evolution of fully-conscious, positive clairvoyance. This implies an extension, which can be hastened by means of self-training, of the normal range of visual response to include both physical rays beyond the violet and, beyond them again, the light of the superphysical worlds…It is important to differentiate between the passive psychism of the medium, and even the extrasensory perception (ESP of parapsychology), and the positive clairvoyance of the student of occultism. This later, completely under the control of the will and used in full waking consciousness, is the instrument of research…to enter and explore the Kingdom of the Gods."

Hodson, Geoffrey: The Kingdom of the Gods, 1953, Theosophical Pub. House, Madras, India. (Page 9)

Suggested Reading –

Katz: You Are Psychic, The Art of Clairvoyant Reading & Healing

Owens: Spiritualism & Clairvoyance for Beginners, Simple Techniques to Develop Your Psychic Abilities

Slate & Weschcke: Psychic Empowerment for Everyone

3.  Although generally used to mean any sort of psychic ability to know, see, hear things from afar, in the future or past, on the spiritual planes, etc., among Spiritualists it is specifically used to mean some form of psychic sight. It can occur to a person either as subjective clairvoyance or objective clairvoyance, and may be challenging for a person having this experience to discriminate between the two. Further, the difference between the two can be viewed as a continuum rather than as an either/or type of experience.