# Today I Learned

Some of the things I've learned every day since Oct 10, 2016

## 92: Order (Groups)

The order of a group $G$, often denoted $|G|$, is the cardinality of its underlying set. If the order is finite, then $G$ is called a finite group, and likewise for infinite order.

An example of a group with finite order would be the dihedral group $D_n$ for some $n$. An example of one with infinite order would be the group of $\mathbb{Z}$ together with addition.