If you don't specify a search description for your blog, search engines will establish one for you based on your blog’s content.
To create your own search description, just go to Settings | Search Preferences and click Edit next to "Description" to reveal a text field. Select Yes, write in your text, and click Save changes.
A few examples of blog search descriptions:
- “A blog about social networking and web design.”
- “A journal of my year in Paris.”
- “Healthy southern-style cooking.”
Enabling this feature will display a “Search Description” option in the Post Settings panel that allows you to enter a search description for individual posts.
For more background on SEO, read through this article in the Webmasters Help Center, and be sure check out their SEO Starter Guide (pdf.
Read more: http://support.google.com/blogger/?hl=en