If you set up one or more galleries for your images, you'll discover that Drupal automatically sorts your images into categories so that you can set up sections for Ceramics, Paintings, Bead Work, and Wood Carvings.

To do this, go to Administer | Content management | Image galleries (at /admin/content/image). Here you will find a list of any galleries you have set up for the site, which will be empty at first. Click on the Add gallery tab and enter a name for your new gallery (which in our case will be Arts & Crafts).

After adding at least one, you may nest new image galleries below others by selecting the appropriate gallery from the parent drop-down selector. You'll also be able to control the order the galleries appear in using the Weight selector: Galleries with a lower number will appear before those with a higher number, and alphabetically if they share the same weight. For instance, you might have Basket Weaving, Candles, and Dryer Lint Sculpture as categories under the Folk Art gallery, which in turn is below the Arts & Crafts.

Now you can go back to your original image, click on the Edit tab, select one of your new galleries from the drop-down list, and press the Submit button. Then browse to Administer | Site building | Menus (at/admin/build/menu). Under the Navigation menu, you will probably see Image galleries (disabled). You will need to enable this menu item for it to show up in your navigation menu by clicking enable at the end of that row and pressing Submit on the following screen.

After doing this, you will be able to see your new gallery by browsing to Image galleries (at image). You will also notice that the breadcrumb changes for your content, so it will list the gallery at the top of the page (with something like Home | Image galleries | Arts & Crafts | Mobiles).

When you visit the gallery page, you will also note that any description you entered for the gallery will be listed there with the thumbnail of the most recent image entered in that gallery to represent it.

The Image Gallery module is actually an extension of the Taxonomy module included in the Drupal core. Taxonomy is one of the many features that allow Drupal to stand out, giving it a way to powerfully control the flow of content through a site.

We won't delve too deeply into the wonderful world of Drupal's taxonomy with its ability to create complex and rich nested, multiple hierarchal vocabularies. It will suffice to say that you can harness the power of taxonomy and folksonomy to organize your site in a logical and useful way that makes it easy for you, your users, and even Google to find exactly what you or they are looking for in seconds.

Gallery categories, although they use the same engine as the rest of Drupal taxonomy, are generally configured and accessed from a different location in the menu tree. This is to allow the gallery to work automatically without any special configuration. Technically, the Image Gallery creates a unique taxonomy vocabulary, and each gallery is a term beneath it. You can see this by browsing to Administer | Content management | Taxonomy (at /admin/content/taxonomy). (In Drupal 5, Taxonomy was sometimes referred to as Categories such as in the menu path.)

You've probably noticed by now that your image is presented in two different sizes, both of which may be different than the original uploaded size. This happens automatically with help from the Image module.

You'll also see that various sizes are available when viewing an image node page: By default, you'll see a link under the image for Thumbnail. If you click on this, you will see the image displayed in a new size and a link to another size labeled Preview, which is the size an image is normally displayed in when visiting its node page.

When you first set up the Image module, two sizes are set up for your site: Thumbnail (at 100x100 pixels), and Preview (at a maximum of 640x640 pixels). The Thumbnail size is displayed when the image is shown as a teaser such as on the front page and on the gallery pages, and the Preview size is shown on the full page.

Though it may be convenient when first setting up a site, for many sites these defaults will probably not be adequate. You may change the sizes your images are displayed in by going to Administer | Site Configuration | Images | Files and sizes (at /admin/settings/image). On this page, you will see text fields for Width, Height, and Link in the Image sizes fieldset. Also, each size may be set to Scale or Scale and crop, which is the second option for creating exact-sized images. (There are settings available for the Default image path and Maximum upload size on the page as well.)

You may change the settings for your Original, Thumbnail, and Preview sizes here. If you have values for both width and height, then the resulting image will be resized to a maximum width by height (in pixels). If you enter only one value, then it will be scaled down exactly to that width or height with the other value changing appropriately to keep the same aspect ratio.

You may add more image sizes here as well. By default, only the Thumbnail and Preview sizes will be shown automatically on the site. But the other sizes will also be made available as links on the image node page. However, you will have access to those new sizes when theming your site. We will cover this later in the book.

The Link settings will configure the links shown at the bottom of the image node page. If set to Same Window and clicked on, the link will display the node page with the new size. If set to New Window, then the link will pop up as an image displayed in a new window. (As a technical note for innovative developers, these link elements will have CSS class elements applied, which could be useful when combined with jQuery to create pop ups with automatically-resized windows.)