A 4D object is a geometric shape that exists in four dimensions, which includes the three dimensions we are familiar with—length, width, and height—plus an additional dimension often referred to as time or a spatial dimension. In mathematics, a common example of a 4D object is a tesseract, which is the four-dimensional analog of a cube. Visualizing 4D objects can be challenging because we live in a three-dimensional world. However, we can represent them in 3D space through projections or shadows. Just as a 3D object casts a 2D shadow, a 4D object can cast a 3D shadow, allowing us to study its properties and relationships in a more familiar context.