Sense data are the mind-dependent empirical ingredients of perception. They are the colours, sounds, smells, tastes and textures upon which the whole experience is built. The idea of ​​sense data is the cornerstone of the theory of Representative Realism, which states that the immediate objects of awareness are not physical objects, but are sense data. Sense data is the mind-dependent subjective intermediaries that provide us with all our knowledge of the external world through a veil of perception, which represents the real world. The theory of Representative Realism is similar to Direct Realism, in that there is an objective, mind-independent physical world; however, we only ever perceive them via a mind-dependent subjective intermediary (called sense data). The idea of ​​sense data is designed to get around many of the problems of common-sense realism. Sense Data successfully explains what illusions are by placing the illusion in a veil of personal perception. For example, take a stick and dip it halfway into water, so that it appears bent. This can be interpreted as a criticism of Direct Realism, because when we see the stick bent, but at the same time feel that it is not, we can assume that one of our senses is deceived and therefore we do not perceive it directly. . However, in Representative Realism, sense data explains this anomaly by placing the inconsistency in the subjective intermediary of sense data. The stick remains straight in the real world, but since all we can see is our sense data, and our sense data is subject to illusion or error, we perceive (incorrectly) that the stick is bent. Hallucinations are another criticism of naive realism, because if we assume the existence of hallucinations, then they cause a big problem for this theory. Since each... central part of the paper... the definition is not physical, so it contradicts itself. However, hallucinations and dreams can appear to us, in much the same way, have shape and form, and yet also remain non-physical, yet they exist. This means that it is possible for sense data to exist, even if the idea is contradictory, but it does not mean that sense data exists with certainty. The claim that we perceive the world via sense data is one possibility. However, even if sensory data explains why illusions, perceptual changes, hallucinations, and time delays occur, it is not necessary to explain these problems. A sophisticated Direct Realist can explain most of these problems just as easily. Since both theories have problems, they can be favored equally over the other; except that Direct Realism is the most systematic, economical, practical and simplest theory, and therefore provides the best working hypothesis.