TITLE: What is the meaning of $\mathbb{R}\setminus\{0\}$?
QUESTION [8 upvotes]: This is used in many posts related to functions and googling it doesn't help.
What does this mean? $\mathbb{R}$ should stand for all Real numbers.

REPLY [7 votes]: Real numbers that aren't $0$. \ is set difference.

REPLY [5 votes]: This refers to the set $\mathbb{R}$ , but without $0$, i.e. the complement of $\{0\}$ in $\mathbb{R}$.