A prediction is a statement or claim that a particular event will occur in the future in more certain terms than a forecast. The etymology of this word is Latin.

A prediction of this kind might be valid and useful if the predictor is a knowledgeable person in the field and is employing sound reasoning and accurate data. Large corporations invest heavily in this kind of activity to help focus attention on possible events, risks and business opportunities, using futurists. Such work brings together all available past and current data, as a basis on which to develop reasonable expectations about the future.

In politics it is common to attempt to predict the outcome of elections through the use of opinion polls. Prediction games have been used by many corporations and governments to learn about the most likely outcome of future events with amazing accuracy.

Predictions have often been made, from antiquity until the present, by resorting to paranormal or supernatural means, such as prophecy or by observing omens. Disciplines including water divining, astrology, numerology, and fortune telling, along with many other forms of divination, have been used for centuries or even millennia to predict or attempt to predict the future. So far none of these means of prediction have been proven under controlled conditions and are heavily criticised by scientists and skeptics.

In a scientific context, a prediction is a rigorous statement forecasting what will happen under specific conditions, typically expressed in the form If A is true, then B will also be true. The scientific method is built on testing assertions which are logical consequences of scientific theories. This is done through repeatable experiments or observational studies.

A scientific theory whose assertions are not in accordance with observations and evidence will probably be rejected. Theories that make no testable predictions remain protosciences until testable predictions become known to the community.

Additionally, if new theories generate many new predictions, they are often highly valued, for they can be quickly and easily confirmed or falsified. In many scientific fields, desirable theories are those which predict a large number of events from relatively few underlying principles.

Quantum physics is an unusual field of science because it enables scientists to make predictions on the basis of probability.

Mathematical models and computer models are frequently used to both describe the behaviour of something, and predict its future behaviour.

In microprocessors, branch prediction permits to avoid pipeline emptying at branch instructions. Engineering is a field that involves predicting failure and avoiding it through component or system redundancy.

Some fields of science are notorious for the difficulty of accurate prediction and forecasting, such as software reliability, natural disasters, pandemics, demography, population dynamics and meteorology.