We have known all along that Google displays several versions of the snippet for a web site in search results, but it looks like they sometimes may use their own version of the title for a web page.
In search engine jargon, a snippet is the brief description for a web page that appears in search results pages. The snippet is generally no longer than 180 characters. With Google, the snippet may be the description meta tag set up by the site owner, the description for the site found in the DMOZ directory, or it may be an excerpt from content found on the web page. The excerpt usually captures a section of the content where the keywords used in a user’s search appear. An excerpt is easily identified by the use of an ellipse (…) before and/or after the phrase displayed in search results.
We can usually influence the text in the snippet that appears. The DMOZ description can be prevented from displaying through the use of a special meta tag. If the description meta tag is carefully crafted, Google will normally use that description.
The description meta tag for each page in a web site should be unique. Do not use the same description meta tag throughout a site or replicate it on multiple pages. The meta tag text should be more than 100 characters and less than 180 characters. It should contain the keyword theme, which is the search phrase or phrases that have been targeted for that page.
Why do we want to try to control the description meta tag? While the description meta tag does not influence a page’s rank positions, it can appear as the description for the web page. The way that the description meta is worded can make a difference between whether a user clicks on your link or one of nine others found on a typical search results page. That means that the wording needs to be compelling and should focus on the the keyword theme for the page.
We have known all along that we can influence the snippet that appears, but we cannot absolutely control it. In some situations Google may also alter the title for the page in their search results. The title for a page displayed in search results traditionally reflected the actual title tag embedded in the HTML/XHTML code for a web page.
Here is what Matt Cutts, a Google quality engineer, has to say about titles and snippets.
The title that appears in search results is the first part of a listing that catches a searcher’s attention. Is important that the title tag focus on the targeted keyword theme. The title tag is critically important with SEO because it is the first place that a spider looks to determine the keyword theme for a web page. If everything comes together, the keyword theme or one of the keyword themes will match the user’s search, which gives the page an advantage in search results.
We have not seen any radical alterations of title tags in Google search results, but we have seen Google plug in their own version of a title tag when it is missing in the web page code. We could therefore assume that Google may simply use their own selected version of a keyword theme if a site owner sets all title tags the same in a site, or if an inappropriate title tag is used, or if the title tag is omitted. This could therefore be good news for people with sites that have not been optimized.