Let's say we need to create a directory `dir` in the path `a/b/c/dir`, but directory `b` and `c` don't exist. In this case, `mkdir -p a/b/c/dir` will create the missing directories in the path.
You can also create multiple directories at a given level. Picture the following directory structure:
```
.
└── wwwroot
├── css
├── images
└── media
├── mp3
└── mp4
```
This can easily be recreated `mkdir -p wwwroot/{css,images,media/{mp4,mp3}}` By using curly braces `{}` you can create multiple directories at a given level.