How do you find the "rank" of a school or program? I am preparing to pursue higher education and I was reading articles about schools. In one of the articles it was mentioned that the author attended a "high teens" ranked school. There was no mention of who ranked this school, how it was ranked, or why. I assume the idea was that I should be impressed by the implication that his school was ranked between 19-16 (my scale for "high" teens).

Who is ranking these schools and what does this number mean? How do I find out my schools ranking?
Anyone can rank schools.

Some rankings are more popular than others (e.g., US News) and some may do so based on particular metrics but there is no de facto ranking system in the world. 

What they actually mean is up for interpretation, and unless they provide the complete methodology then it is rather difficult to find meaning in them at all.