Why does a red shift occur?

A red shift occurs when the wavelength of light emitted by an object is stretched, making it appear more red than it actually is. This phenomenon typically happens when objects in space, such as galaxies, move away from us due to the expansion of the universe. The greater the distance and speed of the object, the more pronounced the red shift. It serves as crucial evidence for the Big Bang theory and helps astronomers measure the universe's expansion rate.