By default, attachments do not have a version query parameter, like, for example JavaScript files have. This plugins adds version numbers to the query strings of attachments.
Version numbers in query strings are useful for caching. If an attachment changes, its version number and, therefore, its URL changes. This allows for the attachment to be cached for an extended period of time or indefintely, for example, with the directive “immutable” of the Cache-Control header.

Attachment URL Version

Adds the version number of attachments to their URL.

Aesqe

“File Gallery” extends WordPress’ media (attachments) capabilities 
by adding a new gallery shortcode handler with templating support, 
a new interface for attachment handling when editing posts, and much 
more… Here’s the full list of features:
Features:
<ol>
<li>multiple galleries per post with custom attachment order</li>
<li>a flexible templating system (PHP, CSS, JS) – choose a different 
template for each gallery, even within the same post (4 templates 
included with plugin)</li>
<li>simple, easy to use UI with drag and drop sorting shows attachment 
thumbnails beneath text editor: everything attachments-related is on 
the same screen you’re editing your post on</li>
<li>fully integrated with the visual editor (tinyMCE) – click on the 
[gallery] placeholder image and change any option in the File 
Gallery metabox – changes will be applied instantly</li>
<li>settings page extends the default media settings page</li>
<li>attach copies of items from media library to current post (copies 
data only, not the file)</li>
<li>copy all attachments from another post</li>
<li>unattach (detach) items from current post</li>
<li>media tags = tag your attachments and then use those tags to choose 
which attachments you want to display in your gallery or to filter 
your media library items.</li>
<li>custom fields for attachments</li>
<li>gallery pagination</li>
<li>different background colors for items in media library depending 
on their status = completely unattached (white), attached to other 
posts (red), or attached to current post (yellow)</li>
<li>compatible with “WordPress Mobile Edition”, “Media Tags” and 
“WPML Multilingual CMS” plugins </li>
<li>basic caching of gallery output and frequent queries (transients)</li>
<li>please see the help file for complete list of features</li>
</ol>
<h3>More info</h3>
This plugin uses icons from the awesome famfamfam Silk icon set by 
Mark James. 
“Silk” can be found at: http://famfamfam.com/lab/icons/silk/
Plugin settings are integrated into media settings page.
Help file is included, you’ll find it in the “help” subfolder.
<h3>Translation Credits</h3>
Hebrew: 
* Maor Barazany – http://www.maorb.info/
French: 
* Jean-Michel Meyer – http://www.li-an.fr/wpplugins/
Italian: 
* Pietro Palli – http://ppal.li/ 
* Francesco Canovi – http://www.blackstudio.it/
Arabic: 
* Wassem Mansour – http://www.sanapix.com
Lithuanian: 
* Vincent G – http://www.Host1Free.com
Polish: 
* Michał Budzik – http://www.mindborn.pl/en/
<h3>Contributors</h3>
Greg Haddow (https://github.com/shaddowgh/) 
Josh Eaton (https://github.com/jjeaton/) 
Andrea Baccega (https://github.com/vekexasia)
<h3>Thanks goes out to…</h3>
<ul>
<li>All the contributors, translators, and people leaving comments, 
bug reports and suggestions on the official page and in the 
WordPress.org forums</li>
</ul>
<h3>Plans for the next versions</h3>
sooner:
<ul>
<li>manage media tags for all selected attachments</li>
<li>audio and video preview on editing screens</li>
</ul>
later:
<ul>
<li>phpdoc all the functions</li>
<li>more detailed description for file_gallery_shortcode function 
(what can be used in ‘orderby’, what do ‘columns’ mean) for beginner programmers</li>
<li>yoxview lightbox http://www.yellow-llama.com/yoxview-gallery-wordpress-plugin/</li>
</ul>
maybe:
<ul>
<li>show attachments’ Custom Fields in the main page of Media Library (custom column)</li>
<li>media library sort by file size or picture dimensions</li>
</ul>
probably not, but who knows:
<ul>
<li>watermarking – probably in another plugin…</li>
<li>when detaching / deleting attachments, just remove them from DOM 
without refreshing the entire file gallery box, but take care of 
originals and copies</li>
</ul>
And thank you for reading this 🙂
aesqe

File Gallery

File Gallery extends WordPress media (attachments) capabilities 
by adding a new gallery shortcode handler with templating support 
(and much more).

Attachment URL Version vs File Gallery