Google may show sitelinks under your result in the SERPs. The system analyzes your site, and if you have three or more sitelinks, it can derive the relevant information and pass it on to the consumer.
This can be a great thing if you have optimized your site correctly. A customer searching for ‘pet products’ when they really want a booties for their dog will appreciate it when a site pops up under the general heading and offers specific sitelinks to get them to their destination faster.
For example, you have a site that sell accessories and clothing for pets. If you have optimized your site correctly, and have deep links to separate pages for cats, dogs, etc then these sitelinks can be displayed in your search results.
The consumer sees ‘dog products’ or something of that sort, and is pleased to be able to simply click on that and be taken directly to where they needs to go. This saves them time as opposed to having to go to your homepage and navigate from there, and makes your site more attractive in the results by offering a direct link to what they are looking for.
That’s the upside to sitelinks. As with every issue, there are potential problems as well. The most popular mistake is not checking all your links on a regular basis. If the click on your links returns a 404 message, or error code, you have probably just lost a customer. They may not wish to waste anymore of their time – the assumption will be, if something is wrong with one of your links, the others may be worthless as well.
Also, some sites with excessive flash components and a lack of good crawlable text may not be as visible to the search engine as a good search result or candidate for site linking. Consider having most of your top landing pages heavy in text and save the gimmicks for advertising and traffic driving.
If you have a feeling that your sitelinks need some work, and might actually be hurting your click through rate, you can block them by using your Google Webmaster tools. Now that you know they are being incorporated, however, looking into how to optimize this feature for your site’s best interest will be the next step up the search engine ladder.