* Redshift: Redshift refers to the phenomenon where light from a distant object appears shifted towards the red end of the electromagnetic spectrum. This shift is caused by the object moving away from us.

* Doppler Effect: The redshift is a result of the Doppler effect, which describes the change in frequency (and therefore wavelength) of waves emitted by a moving source. As the object moves away, the waves get stretched, resulting in a longer wavelength (and a shift towards the red end of the spectrum).

In your example:

* The laboratory wavelength of 321 nm represents the "rest" wavelength of the spectral line.

* The observed wavelength of 328 nm in the distant object is longer, indicating that the object is moving away from us.

The amount of redshift can be used to estimate the object's speed and distance from Earth.