I'm really enjoying the AMS column "What is ..." (<http://arminstraub.com/math/what-is-column>) and The Princeton Companion to Mathematics.


I am looking for something similar. I'd like to acquire some intuition behind different subjects and the general overview rather than digging into details and technical proofs.


I want to read more about the motivation, the greatest results and applications (inside and outside of mathematics). 



Where can I read reviews of mathematical theories?
On the popular level, there is an AMS feature column:
<http://www.ams.org/samplings/feature-column/fc-current.cgi>
and a series of 10 volumes "What's happening in mathematical sciences":
<https://bookstore.ams.org/HAPPENING>,
also by AMS.


On a higher level, there are journals which publish surveys, addressed to
the general audience of mathematicians: Bulletin of the AMS, Russian Math Surveys,
Sugaku expositions, Gazette des Mathematiciens, Expositiones Mathematicae, L’Enseignement Mathématique, and several other such journals.


