People who see the future are visionaries.
They have real visions of future events. These generally have zero context- they appear out of nowhere, without rhyme or reason.
While a vision may seem to be shown on a concrete object, such as a glass, a rock or a water surface, the object is simply a vessel for the vision, and is not endowed with any special psychic qualities of its own.
People who see the future see it within the interplay of light and shadow, and only for a limited time, although the vision may return.
A vision of future events exists only within the mind of the person who sees it.
They actually have no idea about what the things they are seeing really means. They lack context. They mostly do not realize this, though. Many panicked, sensationalized predictions are the result of people seeing the future, but having no real psychic knowledge about future events.
Think about deja vu. When you have experienced an instance of deja vu, you first have a feeling of recognition like, "I know this!" or "This has already happened!" Your next thought or feeling may be, "So that's what it was/meant!" Maybe not every time, but often enough so that you recognize having had this feeling.
So with deja vu, you had (within you) an unrealized vision of the future. But you did not know you had this vision, until the exact events took place. People who see the future, know they have had a vision- but they may never see the actual events take place. In both cases, prediction is not possible because the vision of the future is incomplete.
However, there are a few people who see the future and know it as well. These are psychics who do have the complete picture. They understand what their visions mean, before they happen. Also, the visions they are shown, are the ones with the highest probability of becoming.
***There is always more than one possible future. Some have higher probabilities of happening than others, but at any given moment, the possibilities are limitless. A person with reasonable psychic abilities, who is emotionally stable and grounded in this reality, will not be shown visions of improbable futures.***
The psychic gift of knowing is never really acknowledged, but it is what supports the other psychic powers. It is what makes any conclusions drawn from psychic activities valid or invalid.
What is this gift?
Some aspects differ among those who are blessed with it. In general terms, it is an ability to know or recognize truth. It goes hand-in-hand with whichever psychic power is being used. In this case, people who see the future can know if they are seeing a true vision (one which will likely happen) at the time they receive the image(s). Here, vision is coupled with precognition. Other types of truth-knowing would be (for instance) automatically registering whether a telepathic communication was accurate, or accurately diagnosing a sickness by simply being near someone with it.
For people who see the future and know the future, context is still lacking, however. They cannot answer the questions of how or why what they see will happen. They just know that in some form, it will.
If they keep their visions to themselves, they are likely to be withdrawn- not really fully participating in society. This is mainly because it is stressful to lead two lives- an inner one and an outer one. Visionaries who do this are very high-functioning, probably because the demands are so great.
If they do not keep their visions to themselves, they could suffer worse outcomes. In spite of how enlightened our society likes to think we are, there are systems and strategies in place for dealing with unapproved visions. Seeing things that are 'not' there is definitely not approved of.
On the other hand, if one has complete confidence in their own ability to accurately see the future, and is prepared to take the large risk of societal disapproval, there are fortunes to be made (and this sometimes happens). The only problem is, if your livelihood depends on seeing the future, well you better be seeing it on a regular basis and at predictable times. This kind of pressure means that its only a matter of time before the people who 'see the future' become the people who fake the future.
It is very easy to lose this gift. The best advice for people who see the future is:
The longer you can do these things, the longer you will be able to see the future.
For most visionaries, I would guess they see a few months to a couple of years in the future. Of course there will be cases further out on each end of that spectrum as well- some people will see a few days into the future, others (like Nostradamus) will see 500 years into the future.
There are problems with both ends of the spectrum. If you only see a few days into the future, you are too close to it to be fully emotionally detached from what you are seeing. So, even though familiarity with people and events could help you interpret what you are seeing, wishful thinking will affect your insights.
But seeing centuries into the future, while allowing you to be less emotional and more analytical, also has problems. As you are completely unfamiliar with people, events and technology that far away, you cannot put what you are seeing into context. What might seem a tragedy, could be a triumph, and vice versa.
People who see the future need to be aware of these possible pitfalls, and act in a way that minimizes any damage that could come about as a result of their visions. Visionaries need to be socially responsible, above all.