I've never heard of it before, and it makes perfect sense what it is from that intro.
On a celestial sphere (planet, star, etc) the declination angle (being 0 is at the equator, being 90 degrees is the north pole of the sphere, being -90 degrees, is at the south pole).
You also need another angle known as the "hour angle" to locate a point on the sphere. It doesn't explain what that is, but as can be seen on Wikipedia, you can easily click on that word to go to the entire page that explains what it is.
Well that was a whole other topic. And luckily it links to a page that explains the whole topic of what a "celestial sphere" is. Going to the page, I see I was indeed wrong about what it was, but now I see it is an abstract sphere, with a radius that can be whatever size you want, and that is centered on the Earth, or on the observer.
Once again, not so difficult to figure out even if you have no experience in the specific technical field of a Wikipedia article. So I have no idea what /u/casenmgreen's problem is.
On a celestial sphere (planet, star, etc) the declination angle (being 0 is at the equator, being 90 degrees is the north pole of the sphere, being -90 degrees, is at the south pole).
You also need another angle known as the "hour angle" to locate a point on the sphere. It doesn't explain what that is, but as can be seen on Wikipedia, you can easily click on that word to go to the entire page that explains what it is.
What don't you understand?