It's most common use is to take some stuff on stdin and then use those as arguments to a command. Here is a fancy way to do `ls * `[1] using xargs:

    find . -print | xargs ls

`find` dumps the results to stdout, the pipe shuttles `find`'s stdout to `xargs` stdin, `xargs` uses its stdin as arguments for `ls`.

(Don't run this in your home directory)

[1] Pedants will realize this is actually equivalent to `ls .* *` as hidden files are found by `find`.