Reality

Reality is something that is really true. Reality is mind-independent, i.e. reality would continue to be the case whether or not anyone believed it, or indeed whether or not there were any minds to believe it in the first place.

"That which, when you stop believing in it, doesn't go away." -- Philip K. Dick

Something that is said to be "a fact" is a concept, statement, thing, scientific law, or event that has been unequivocally (indisputably) proven to be true. Facts are always based on concrete verified evidences which substantiate their truth.

M. Scott Peck described sanity as "dedication to reality at all costs".

Ontology is the branch of philosophy that deals with the study of reality.

An entry in a physics glossary:

• We say that science studies the "real" world of perception and measurement. If we can apprehend something with our senses, or measure it, we treat it as "real". We have learned not to completely trust our unaided senses, for we know that we can be fooled by illusions, so we rely more on specially designed measuring instruments. Yet much of the language of science has entities that are not directly observable by our senses, such as "energy", and "momentum". These are, however, directly related to observables and defined through exact equations. Philosophers may argue whether the "real" world exists, but so long as our sense impressions and measurements of this real world are shared by independent observers and are precisely repeatable, we can do physics without philosophical concerns. [1]