Final answer:
The Hubble constant represents the rate at which the universe is expanding. It is determined by measuring the slope of a graph of velocity versus distance obtained from redshift measurements.
Step-by-step explanation:
The Hubble constant is a central concept in cosmology that represents the rate at which the universe is expanding. It is determined by taking the slope of a graph of velocity versus distance obtained from redshift measurements. For example, if the Hubble constant is 70 kilometers/second/million parsecs, it means that galaxies are moving away from us at a speed of 70 kilometers/second for every million parsecs of their distance.