I have not written this plugin myself.

I found it on http://vim.wikia.com/wiki/Deleting_a_buffer_without_closing_the_window and it is to my best knowledge licensed with a CC-BY-SA license (full license text here: http://creativecommons.org/licenses/by-sa/3.0/legalcode).

It is for deleting a buffer in Vim without closing the window.

The reason for adding it here is to be able to add it to an existing Janus bundle (look at https://github.com/carlhuda/janus for instructions on how to do that).