Three units used to measure distance to stars?

The nearer stars are measured by triangulation using the radius of the Earth's orbit as the basic yardstick.

Friedrich Bessel discovered parallax in 1838, the slight movement of a star against the background of more distant stars caused when the Earth orbits around the Sun. He picked out a star that he suspected was close, called 61 Cygni, and found that it was at a distance of ten light-years.

This method is used for stars out to about 200-300 light years.