Clairvoyance, produced from a 17th Century term meaning clear vision, is a type of ESP - Extra Sensory Perception. Although usually used to describe a number of psychic abilities, such as second sight, telepathy, prophetic thoughts and psychic goals, it is strictly speaking an ability to discern information regarding a person, object, location or event via perception other than from the usual five senses. A person gifted with this ability is called a clairvoyant - a person who sees clearly.
In parapsychology, the term clairvoyance is used purely to describe information - both in the present time and not readily accessible to the particular clairvoyant - coming from an external source, instead of telepathy, where information is moved from one mind to another. In other words, a email has the ability to see or even visualise events, objects or persons outside the capability or array of physical sight.
Remote viewing, usually a governed, specific process, is really a facet of astro voyance, as is clairvoyant dreaming. For instance, chances are you'll dream about a location they have never seen before and later find it is exactly because they had visualised it inside their dream.
This became of me, for example, once i was about to start my personal first term at college. As I had never visited the city where the school was located, my dad offered to take me there in order to find just how from the train station towards the college. Having dreamt about it the night just before we went, I had been able to lead him to the college along the shortest path possible, knowing exactly where and when to turn. I had been even able to tell him how long it would get us to get right now there.
However, outside of the area of parapsychology the term is generally used to describe other types of paranormal, or anomalous, perception. Generally, it is used in relation to its the perception of earlier (retro cognition) or perhaps future (precognition) events. This is a gift many have got without even realising it. To use another personal experience as an example (and I do not claim to be a clairvoyant in any way), a few years ago, a friend's daughter had gone into hospital at the beginning of the evening to have the girl first child. Whilst with a group of shared friends around 10 PM, someone suggested we should phone the hospital and find out exactly how she was making. As one of them found the phone, I announced that a call will be wasted, as she'd have a little boy in the early hours of the pursuing morning. We called anyway and were advised she was asleep as the labour experienced slowed. My friend said the next morning which her grandson came to be at 5:30 AM.
Frequently, mediums will also refer to the actual perception of images identified during communication with spirits as clairvoyance.
In any case, clairvoyance is a precious gift which can and should be utilized in order to help as well as guide others.