Extensions are the glue between WP/LR Sync and gallery plugins or the themes. However, you don’t need those extensions if you are only synchronizing with the Media Library. Make sure you also read the introduction on the main page of WP/LR Sync before reading this.
The extensions are available in your admin in WP/LR Sync > Extensions. You will see a screen that looks like the one below.
In the screen above, the Post Type internal extension has been checked. Notice the message at the top of the screen. This extension is loaded and working. Extensions can also automatically be created and loaded by a theme or another plugin, in that case that message will also display that information.
Select one (or more) extension(s) and click Save Changes. Then click on Resync with Extensions. WP/LR Sync will share all the information (about the collections, folders, keywords and so on) to this extension and everything you need will be automatically created. Then, from now on, everything will be kept in sync through those extensions as well.
Sometimes, an extension can add a menu to your WP/LR Sync menu so make sure you check it out. In the case of the Post Types extension (which is a powerful one), there is a new menu. Check the options for it. There is also a little presentation of this extension here.
Not happy with this extension? You can Reset with Extensions to remove all the data linked to this extension, switch to another one, save, then sync again. It is very easy to switch between extensions with WP/LR Sync. That way, you can also test and play as many themes are you want without having to re-create everything by yourself too.
Once you are happy with an extension, just forget about WP/LR Sync. It will keep your WordPress synchronized with your Lightroom naturally.
Internal Extensions are the ones directly available in the plugin. External Extensions are the one developed outside (which also means you can make your own one) and they support specific plugins and themes.
This extension allows you to link and sync:
With this extension, you will be basically able to sync most themes’ post types and taxonomies automatically. That taxonomies can create those post types / taxonomies and even re-use existing ones.
This extension creates a new post type called Collection. Your collections and sets will be replicated in in WP with the same hierarchy. The title will be be kept synchronized the one you are using in LR. This extension is quite simple and is meant to be used as an example. You can look at its code and adapt it to your needs.
I recommend you to use the galleries shipped with the themes and/or in general to use the simple gallery short-code available in WP instead of gallery plugins (avoid especially heavy un-interchangeable plugin such as NextGen). They have a tendency to do too much and not very well.
You can create your own extension based on those previous ones. It’s not difficult and can be a lot of fun to develop! 🙂
If you would like to have your collections available in your gallery plugin or theme through WP/LR Sync, contact your theme developer and let him know about this. I will collaborate with the developer.