A thumbnail is important because it is a preview image that visually ties in with the content that is written below it. Thumbnails help the users understand context better and relate to it. Since users often skim through websites, a visual cue may entice them to click on the article. Your thumbnails also carry your website’s branding. These thumbnails are part of your design system. Even though each thumbnail has to be relevant to the topic, it also has to also be able to connect to your branding strategy.