The prediction of the future by most of the methods like astrology (vedic or western) are based on mathematical calculations. Psychic predictions, on the other hand, are not mathematical, and to most of us don't even sound logical. Psychics have their tools too, such as crystals, cards, pendulums, etc. However, the predictions offered by such psychics are not based on any kind of logic or calculation. It is primarily based upon their intuitive skills. These intuitive skills are either present from birth, or can be steadily developed using several meditative methods.
All of us have within us a conscious and a sub-conscious self. The intuitive capabilities are within the domain of the sub-conscious. It may manifest in different styles for different people. For example, someone may see predictive dreams, someone may experience visions, or someone may hear things, and so on. There is no logical explanation for a lay person as to how or why these phenomena occur.
A psychic is someone who has achieved a considerable amount of connection with his or her inner self or sub-conscious self. He/she may often use a tool or an aid to actually form such a connection. Crystal balls or tarot cards are very good examples of such tools. These tools provide the necessary 'jump' required for such a person to launch himself/herself into some kind of a meditative trance-like state, where they may be able to see or feel things.
There are some among us who have a deep empathic ability. They can enter a room and sense what has occurred or what will happen in the near future. They can also sense if a person is happy or sad. Then there are others who know beforehand if the doorbell or the phone is going to ring, or if it does ring, they know who is there on the other side. These are inherent qualities present within all of us. However, the psychic has developed these qualities either consciously or unconsciously.
There are therefore, different names for certain specific psychic abilities. A clairaudient psychic is someone who hears things. A clairvoyant psychic is one who sees things. An empath is someone who senses or feels things.
Psychic predictions, therefore, can often be quite startling and clear, and may provide an individual with a lot of insights into a situation. It has also been said that these abilities are the function of a certain chakra within our body. The third-eye chakra, for instance, gives one the capacity for clairvoyance. If the chakra has become activated, a person will begin to possess these capabilities.
Many eastern mystics spend considerable amount of time in meditations. These activities also serve to calm the 'mind' and open or activate the chakras. Western mysticism also has a variety of processes, whereby, a person's psychic capabilities are activated or enhanced. However, both these methods require a lot of dedication and practice.
If we look around, we will find many professional psychics who make predictions. of course there are many who are simply frauds and looking to make a fast buck. However, there are some who are genuine too. The presence of a bad apple does not necessarily make the whole stock of apples bad.