There are often complaints in the forum that Google is not showing your title tags in the search results properly.
Yesterday, Google wrote a blog post named Better page titles in search results. Here, Pierre Far, explains why Google may pick a different title tag.
In a Google+ post he gives the short version:
- Our algorithms generate thee alternative titles so that your page is no longer constrained with having just the one title for all the different queries your page ranks for. This has the nice side effect of making the result look more relevant to our searchers and...
- On average, the alternative titles increase the clickthrough rate on the results, i.e. more traffic for you.
- The <title> tag is still a primary source for titles we show so all our advice about make them concise and useful and enticing still very much apply. Keep an eye on the HTML Suggestions page in the Diagnostics section in Webmaster Tools for title suggestions.
For a more detailed walk through of this, see the Google Help document on this topic.