Google started to show related brands for generic shopping-related queries. The suggestions are similar to the ones from Google Product Search and they're used to refine the results.
For example, if you search for [mp3 players], Google shows brands like Sony, Creative Zen, SanDisk. If you click on [Sony], Google will show the search results for [Sony mp3 players]. For some reason, the most popular brand of MP3 players is not included.
"Sometimes when searching for product information on Google, you may not know some of the brand names relevant to your particular search. So, we wanted to make it easier for you to find the brands other people consider useful for popular product searches. Determined algorithmically, these highlighted brand names may help you find what you're looking for faster, and make your research and shopping experience all the more enjoyable," explains Google.
The results aren't always great, especially for complex queries:
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