Pierre explains that apart from the many signals used, Google still considers the tag as the primary source of a title for your page and then decides which title to show to users. But it often so happens that webmasters use the same title tag for all or some pages on their website which might not be the best one to be shown for all keywords relevant to the site.

Google has some algorithms that generate alternative titles to make it easier for users to recognize relevant pages in your website. After doing some testing Google found that these alternative titles are generally more relevant to the query and can substantially improve the clickthrough rate of a webpage that is beneficial for both the searchers and webmasters. And that is the main reason why webmasters see an alternative title for their web pages.

Apart from this Google also tries to replace unnecessarily long or hard-to-read titles with more ‘to the point' and descriptive alternative titles so that searchers can get a quick indication of what the webpage is actually about. On other occasions, Google has also found irrelevant titles are displayed for pages that have no title or a non-descriptive title that might be leaving the searchers confused. For example, a title using simply the word "Home" is not really indicative of what the page is about.

Pierre further explained that Google has always advised webmasters to create unique page titles and meta descriptions for the snippets as these two elements are the first thing a potential customer views in the SERP's and then decides whether or not to click and enter the website.

To help webmasters who are still facing problems in writing better titles and meta-descriptions, Google has updated their Help Center article on this topic.