Mkdir
mkdir (make directory) can be used to create a new directory.
[edit] 1 Examples
[edit] 2 Making one or multiple directories
Create one directory:
mkdir dirname
Create multiple directories:
mkdir dirname1 dirname2 dirname3
Create a directory inside an existing directory:
mkdir basedir/dirname1
[edit] 3 Making directories inside directories
If you want to create a folder inside of a folder that doesn't already exist yet:
mkdir -p newdir/dir1
And both newdir and dir1 will be created. You can go as deep as you like. The -p option will create the whole path if any of it does not exist.