How do I close a single buffer (out of many) in Vim?

I open several files in Vim by, for example, running

vim a/*.php

which opens 23 files.

I then make my edit and run the following twice

:q

which closes all my buffers.

How can you close only one buffer in Vim?

Answer:

A word of caution: "w does not stand for write but for wipeout!"

More from manuals:

:bd

Unload buffer [N] (default: current buffer) and delete it from the buffer list. If the buffer was changed, this fails, unless when [!] is specified, in which case changes are lost. The file remains unaffected.

If you know what your're doing, you can also use :bw

:bw

Like |:bdelete|, but really delete the buffer.