In mobile search results for a complete website, such as the main page, Google is now only showing the site names.
In mobile search results for the complete website, such as in queries for a website’s name, which typically display the main page, Google appears to have stopped displaying title tags.
For subdomains, this feature is not functional.
In smartphone searches, only a website’s generic name is displayed.
As an illustration, the search engine results page (SERP) for Search Engine Land on a mobile device displays the website’s general name, Search Engine Land.

The home page’s title is
<title>Search Engine Land – News, Search Engine Optimization (SEO), Pay-Per-Click (PPC)
The title tags appear to still be displayed for keyword searches that are not branded. Searches using a brand name and related keywords also seem to display the title tags.
Why Use Site Names in Google Searches?
Google uses site names to help users quickly identify a particular website in the search results.
The following several months will see the introduction of this new feature in additional languages in addition to English, French, Japanese, and German.
New Feature Isn’t Always Effective
The same search results that included the new site names as the title link are returned when searching for a compound word domain name like “Search Engine Land” and “searchengineland”.
However, a search using the domain name HubSpot returns the title-tagged old version of the search results.

But a search for Hub Spot (with a space between the two words) does work and shows the site name.

A Structured Data Feature for New Site Names
The use of the WebSite structured data type is advised by Google.
Prior to today, it was thought that the WebSite structured data site had no purpose because Google already knew that a website was a website and didn’t require structured data to know that it was indexing a website.
The “name” field of the WebSite structured data type, in particular, is now used by Google to determine what the site name of a website is, hence this has changed.
A WebSite structured data example using the “name” property was published by Google:

What Happens If a Site Has a Different Name?
The ability to inform Google about the website’s alternative name is what makes the website structured data useful.
The structured data for the optional name is presented as follows:

Google Utilizes More Than Structured Data
According to the Google guidelines on site names, in addition to structured data, Google also considers on-page, off-page, and meta data information when determining what a webpage’s site name is.
Google interprets the site name using the following:
- Structured data on websites
- Headings (H1, H2, etc.)
- Metadata from the Open Graph Protocol, notably the og:site name
Google Site Names
On mobile devices, the new Google search tool that displays site names is appealing.
For home page brand name searches, there should be less clutter in the SERPs. Although we imagine some people grumbling about the title tag’s lack of impact in these searches.
Source – site name in Google search