How do the search engines decide what snippets to include in the search engine results pages? Is there one method or is there one method per search engine? No, I think not.
Google, for instance, will sometimes take your meta description and make that your SERP snippet. Other times, they will borrow the description from DMOZ. And quite often the search engine will pull text off a particular page to use as the SERP snippet. In fact, you can conduct one search and get one snippet then conduct a related but different search and get a different snippet for the same page. It happens all the time.
For example, if I search for “Dave Matthews Band” I get the following for a snippet in the Google SERP:
DMB to Perform on David Letterman 7.27 & 7.31 … DMB Beacon Theatre Show and
Interview Blog with Dave Available on Hulu. New DMB Studio Album …
Dave Matthews to Perform at Farm Aid on October 4th in St. Louis, MO · DMB
iTunes Pass Update · DMB Beacon Theatre Show and Interview Blog with Dave …
Both of these snippets is for the Dave Matthews Band website home page. Different snippets for slightly different searches. I think we can learn from that.
You have to be conscious of just what searches may be looking for when searching for information you provide. Instead of focusing each page on one keyword, expand its search engine optimization by including related keywords that are completely different. For instance, “widget” may be your primary keyword, but you could also include “gadget” as a secondary keyword and “thingamajig” as a tertiary keyword. That way, if someone is searching for “widget” or “widget thingamajig” then you increase your chances of being found for both keywords. Just understand that the snippet for each search will likely be different.
OK, that’s an example for synonymous keywords. But what about non-synonymous keywords? You can do it there too. For example, “red wheelbarrow” may be your primary phrase. But “poem” and “William Carlos Williams” could be secondary and tertiary phrases. Anyone searching for “red wheelbarrow” may find a page on your site, but what if they search for “red wheelbarrow poem” or “red wheelbarrow williams”? Better yet, what if they search for “red wheelbarrow poem williams”? It is likely, if you use all of those keywords on your page, that your page will show up for the search results and a different snippet will appear for each search phrase. Leave out one of those keyword phrases and you could be missing opportunities.