What is column density in astronomy?

[ray_mcintos]

TL;DR Summary

I have read about column density but I am unable to get a clear idea about it.

What is column density in astronomy?

 

[berkeman]

Welcome to the PF.

Summary:: I have read about column density but I am unable to get a clear idea about it.

What is column density in astronomy?

Could you post some links to your reading so far, and point out what is confusing? Doing a Google search on your thread title turns up lots of good hits, IMO...

https://en.wikipedia.org/wiki/Area_density

https://academic.oup.com/mnras/article/400/4/2050/1746878

http://www.as.utexas.edu/astronomy/education/spring02/scalo/aikawa.pdf

 

[ray_mcintos]

https://iopscience.iop.org/article/10.1086/680323/pdf

Section 4 in the above link, I was trying to understand the way to calculate but I am not clear about the derivation and in the section 15 there are some examples of column density calculation that one too.