TITLE: What does this notation mean: $\displaystyle\lim_{\leftarrow} \,\mathbb{Z}/n\mathbb{Z}$?
QUESTION [8 upvotes]: Just a small notation question from this Wikipedia page:

The absolute Galois group of a finite field $K$ is isomorphic to the group  $$\hat{\mathbb{Z}}=\lim_{\leftarrow} \mathbb{Z}/n\mathbb{Z}.$$

What does the $\displaystyle\lim_{\leftarrow}$ part mean?  Why is it written like that?

REPLY [5 votes]: It is used to denote the inverse limit as opposed to the notation $\displaystyle\lim_{\to}$ which is used to denote the direct limit.