Those are called sitelinks. Here is Google's explanation:
We only show sitelinks for results when we think they'll be useful to the user. If the structure of your site doesn't allow our algorithms to find good sitelinks, or we don't think that the sitelinks for your site are relevant for the user's query, we won't show them.
At the moment, sitelinks are automated. We're always working to improve our sitelinks algorithms, and we may incorporate webmaster input in the future. There are best practices you can follow, however, to improve the quality of your sitelinks. For example, for your site's internal links, make sure you use anchor text and alt
text that's informative, compact, and avoids repetition.
If you think that a sitelink URL is inappropriate or incorrect, you can demote it. Demoting a URL for a sitelink tells Google that you don't consider this URL a good sitelink candidate for a specific page on your site. Google doesn't guarantee that demoted URLs will never appear as a sitelink, but we do consider a demotion a strong hint that we'll try to honor when generating sitelinks.
Demote a sitelink URL:
- On the Webmaster Tools Home page, click the site you want.
- Under Site configuration, click Sitelinks.
- In the For this search result box, complete the URL for which you don't want a specific sitelink URL to appear. (How to find the right URL.)
- In the Demote this sitelink URL box, complete the URL of the sitelink you want to demote.
Once you've demoted or undemoted a sitelink, it can take some time for search results to reflect your changes.
You can demote up to 100 URLs, and demotions are effective for 90 days from your most recent visit to the Sitelinks page in Webmaster Tools.