what is the default sorting order for entries returned by the linux find command?

For example, if I issue 

```
find . -type f -name '*mp3' 

```

and the output consists of multiple files across multiple sub-folders, what is the default order in which directories are listed? At the same time, what is the sorting order in which files within an individual directory are listed?

Sometimes it returns:

```
./B/01.mp3
./A/01.mp3
./A/04.mp3
./A/02.mp3

```

See how first the contents of directory B is listed, then that of directory A. At the same time within directory A, files are listed in a funny order.