Illusions have stumped people for ages, using moving pictures and sounds that do not make sense. These phenomena occur when the brain lacks information and fills in the gaps, creating its own reality. Illusions help us understand how the brain processes what we perceive through our senses, including sight, hearing, and touch. There are many types of illusions that happen due to an error in the brain, but this error can be used by scientists, artists, and developers to improve the human experience.

            There are several types of illusions. Optical illusions are the most well-known. They affect vision, creating shapes, patterns, and colors that defy reality. Examples include ambiguous figures, moving pictures, and images that change based on perspective. The next type of illusion is auditory illusions.  Auditory illusions trick our sense of hearing. One example is the falling bells illusion, where a sound seems to get lower in pitch while actually getting higher in pitch. Some auditory illusions make us hear patterns or words that are not there. The last and most tricky illusion is the Tactile and multisensory illusion. Tactile and multisensory illusions use the sense of touch. The rubber arm illusion, for example, makes a person believe a fake rubber arm is that person's own. These examples show that illusions affect more than just our eyes.

            Illusions occur due to the way the brain interprets information. When the brain does not have all the information, it uses perceptual inference to fill in the gaps. Perceptual inference is when the brain uses both past experiences and context to construct our perception of reality. Perceptual inference can sometimes be flawed. Psychologists often use the terms top-down processing (using prior knowledge, expectations, and context) and bottom-up processing (using external stimuli). Illusions occur when these processes do not correlate, requiring the brain to bridge the gap. While the brain is a vital part of the body, it can also make mistakes.

            Illusions are more than just a joke; they are used to improve art, science, and technology. Illusions confuse the brain, making it focus on the illusion. Some famous artists, like M.C. Escher, use illusions for this purpose, to captivate the audience and make them remember the work of art. Illusions are not just used in art; they are also used to improve technology and design. Virtual Reality (VR) is a big example of the use of illusions in technology. After a person puts a VR headset on, there is depth in the game, which is an illusion caused by showing different images to each eye. While these are concrete examples, science uses illusions more abstractly. Scientists have learned more about how the brain functions in relation to how different people perceive the illusion. A good example of a useful illusion is the Rorschach test. The Rorschach test is a series of random ink splatters that can determine how someone thinks and how they have grown up, depending on what image they see in the inkblots. The Rorschach test is one of the most basic uses of illusions in science. Thusly, illusions have a big impact and many uses in the world.

            Many different types of illusions occur as a result of an error in the brain, allowing artists, scientists, and developers to create art and improve technology to enhance people's lives. Optical illusions, auditory illusions, and tactile and multisensory illusions each trick a different one of the five senses but work similarly. They force the brain to fill in missing data. While illusions are an error in the brain, they are essential in developing art and technology, as well as helping scientists further the understanding of how one's environment impacts them.