Google has added a sorting feature to Google Images. The goal is to help you find the image you're looking for, even if you can't exactly describe in words what you want to find.
Google says sorting will be rolling out globally to nearly every domain and language over the next week. The company has been testing the new feature for a while, and now it's finally ready for public consumption.
You still have to input a query, but after turning on sorting (click on "Sort by subject" in the left-hand panel), you will also be able to see other similar queries and their results. They're almost like search suggestions, except you they're presented as images, which makes sense because when using Google Images, you're looking for visual content and aren't necessarily thinking in words.
Sorting by subject reorganizes the images into categories that will narrow down your search and help you find the image you want. It shows some of the most popular images, and their associated queries, which are similar to your query. You can then click on a given category to find the best image within that subject group.
Sorting by subject uses algorithms that identify relationships among images found on the Web and presents those images in visual groups. By looking at multiple sources of similarities, such as pixel values and semantic relationships, and by mining massive amounts of data, Google can make connections and groupings among images. If you remember Google Similar Images and Google Image Swirl, you can think of this feature as their successor, as it uses the same technology.