WordPress.org

I installed your plugin, but when I click on a thumbnail, the original picture is loaded directly instead of in the Colorbox. What could be the problem?
Make sure that your theme uses the wp_head(); function in the HTML head-tag.
I have seen problems where other plugins include their own versions of the jQuery library my plugin uses.
Chances are that the other jQuery library is loaded after the one that I load. If that happens, the colorbox features are overwritten.

How does jQuery Colorbox work?
When inserting a picture, the field "Link URL" needs to contain the link to the full-sized image. (press the button "Link to Image" below the field)
When rendering the blog, a special CSS class (colorbox-postId, e.g. colorbox-123) is added to linked images.
This CSS class is then passed to the colorbox JavaScript.

How do I exclude an image from Colorbox in a page or post?
Add the CSS class colorbox-off to the image or to the link to the big sized image you want to exclude.
jQuery Colorbox does not add the colorbox effect to images that have the CSS class colorbox-off.

How does jQuery Colorbox group images?
For all images in a post or page, the same CSS class is added. All images with the same CSS class are grouped.

I have Flash (e.g. Youtube videos) embedded on my website. Why do they show up over the layer when I click on an image?
This is a Flash issue, but relatively easy to solve. Just activate the automatic hiding of embedded flash objects on the settings page.
Adobe described on these sites what the problem is and how to fix it manually:
Adobe Knowledgebase 1
Adobe Knowledgebase 2

I have a problem with the Colorbox or want to style it my own way. Can you help?
Of course I want to help everyone, but I have a full time job and I don't have the time. You can ask your questions at the Colorbox Google group.

Why is jQuery Colorbox not available in my language?
I speak German and English fluently, but unfortunately no other language well enough to do a translation.
Would you like to help? Translating the plugin is easy if you understand English and are fluent in another language.

How do I translate jQuery Colorbox?
Take a look at the WordPress site and identify your language code:
e.g. the language code for German is de_DE.

1. download POEdit
2. download jQuery Colorbox (from your FTP server or from WordPress.org)
3. copy the file localization/jquery-colorbox-en_EN.po and rename it. (in this case jquery-colorbox-de_DE.po)
4. open the file with POEdit.
5. translate all strings. Things like {total} or %1$s mean that a value will be inserted later.
6. The string that says "English translation by Arne ...", this is where you put your name, website (or email) and your language in. ;-)
7. (optional) Go to POEdit -> Catalog -> Settings and enter your name, email, language code etc
8. Save the file. Now you will see two files, jquery-colorbox-de_DE.po and jquery-colorbox-de_DE.mo.
9. Upload your files to your FTP server into the jQuery Colorbox directory (usually /wp-content/plugins/jquery-colorbox/)
10. When you are sure that all translations are working correctly, send the po-file to me and I will put it into the next jQuery Colorbox version.

My question isn't answered here. What do I do now?
Feel free to open a thread at the jQuery Colorbox WordPress.org forum.
I'll include new FAQs in newer versions.