The most useful distance measurement in measuring the distances between stars is the parsec. A parsec is defined as the distance to an object that has a parallax angle of one arcsecond. This means that if you were to observe an object from two different points in space, separated by a distance of one parsec, the object would appear to move by one arcsecond in the sky.

Parsecs are commonly used to measure the distances to stars within our own Milky Way galaxy, as well as to nearby galaxies. For example, the closest star to our Sun, Proxima Centauri, is located about 1.3 parsecs away. The centre of our Milky Way galaxy is about 8,000 parsecs away.

For measuring distances to objects that are even further away, such as other galaxies or quasars, astronomers use different distance measurement methods, such as the redshift method or the standard candle method.