Google this week introduced a new new system of generating titles for web pages in search results. Google no longer is using user's query to generate titles. Instead, this new system generates titles from the main visual title or headline shown on a page, or from the content that’s large and prominent through the use of style treatments.
Google confirms that content from HTML title tags is still by far the most likely used, more than 80% of the time.
Google faces a problem, when some publishers use very long titles, stuffed with keywords, and often there are cases where pages are called “Home” or pages “Untitled” or only have the name of the site. Google clarifies this is the reason that more than HTML title tags are used.
Google says the update is designed to produce readable and accessible titles for pages. Google may add site names where that is seen as helpful or shorten a title selecting the most relevant portion.