The term "4D" refers to a four-dimensional space that includes three dimensions of space (length, width, height) and an additional dimension, often considered time. In physics, this concept helps to describe the behavior of objects in the universe, particularly in the context of Einstein's theory of relativity, where time is intertwined with the three spatial dimensions. In popular culture, "4D" is often used to describe immersive experiences, such as in 4D cinema, where viewers not only see a film in three dimensions but also feel physical effects like motion, wind, or scents. This enhances the storytelling by engaging multiple senses, making the experience more interactive and realistic.