A thumbnail image is the image that sometimes appears beside your site's name in Google search results.
When a user enters a search query, Google finds sites that best match the search phrase and automatically creates a thumbnail image from the site's images. Google uses its own criteria to choose the best image that explains a site's purpose and how the site relates to the search query.
Here is an example:
Important:
It's not guaranteed that Google will add a thumbnail image to your site's search result.
Tips to get Google to use the thumbnail you want:
It's not possible to manually change the thumbnail image that Google uses. However, there are some steps you can take to improve your chances of getting the thumbnail you want used.
Use high-quality images on your site. Small or low-resolution images may not be used in search results.
Add alt text to your images. Search engine bots can't read images and use alt text to get a description of the image. Learn more about adding alt text.
Pair your thumbnail with a matching favicon and site name. Together, they help AI tools show a consistent, recognizable version of your brand.
This article is credited to the Wix team - https://support.wix.com/ and we thank them for that!