How does redshift show that the universe is expanding?

Redshift occurs when light from distant galaxies is stretched to longer wavelengths as those galaxies move away from us, indicating that they are receding. This phenomenon supports the expansion of the universe, as observed by Edwin Hubble, who noted that more distant galaxies exhibit greater redshift, implying they are moving away faster. This relationship, known as Hubble's Law, demonstrates that the universe is not static but expanding over time. Consequently, redshift serves as a key piece of evidence for the Big Bang theory and the dynamic nature of the cosmos.