What evidence indicates that the universe is expanding?

redshift and doppler effect
redshift is an increase in the wavelength of radiation emitted by a receding celestial object as a consequence of the Doppler effect and the Doppler effect is a tool used to measure frequency changes as light travels to, from, or pass an observer

Which one is the underlined word?

Maybe on the physical part? i dunno i just guessed plus i really need the points