TITLE: Good blogs for undergraduate mathematics?
QUESTION [5 upvotes]: I search some useful blogs talking about undergraduate and graduate mathematics, like terry tao
So any suggestions? Thanks in advanced.

REPLY [2 votes]: It depends on which subjects you are considering. Two suggestions would be:

General Topology: https://dantopology.wordpress.com/ - an excellent blog on undergraduate and higher-level topology
Some Linear Algebra, Probability, and Olympiad-style questions: https://eventuallyalmosteverywhere.wordpress.com/ 

The general rule seems to be that such blogs are written by PhD students with the aim of either giving support to the undergraduates in the courses the PhDs are TA-ing, or with the aim of better structuring their own knowledge on the subject in which they're doing research. Thus, you would find at most 2-3 subjects covered satisfactorily in such a blog.