Named after the size of the human feature, an Image Thumbnail is a small image included alongside certain organic search results. When an image is included in this way, it’s understood to generate more traffic. Images that are relevant to the search query are more successful at generating traffic than those that are not.
Thumbnails act as visual previews of a webpage, and work alongside a meta description of that page. Optimising both the image and the meta description is understood to generate more clicks. Categorised as an organic SERP feature, the Image Thumbnail appears in cases where SERPs feature organic search results.
