What is a thumbnail?

A thumbnail is a small preview image that stands in for a larger version of the same image or for the content behind it. The word literally describes the size of a thumbnail; in a digital context it is closer to preview image, image preview or miniature image. Thumbnails usually work as placeholders, and the full-size file is only loaded when someone actually asks for it.

Why are thumbnails important?

Unlike text, an image catches the attention of potential customers very quickly. Once the interest is there, the thumbnail gets clicked, which in turn raises the interaction on the website.

Where do you come across thumbnails today?

On video platforms such as YouTube you can upload a separate thumbnail for every video. Those images are shown before a visitor clicks the video, so the choice of image can decide whether a video is picked and played at all.

In the content management system WordPress, for example, every post can be given a featured image. These images are previews of the article behind them.

The first view of image search in search engines like Google is made up of thumbnails as well. Only when you click one of them does the real image load at full size.

What are the SEO benefits of thumbnails?

Since loading speed became an important ranking factor for search engines, thumbnails carry one fundamental advantage for SEO: they reduce the total size of a page. Because certain graphics are only loaded at their original size when they are actually needed, which is the same principle behind lazy loading, thumbnails slim down the file weight of a page. The less data a browser has to load, the faster the page can be displayed. Image weight is one of the standard checks in an SEO audit.

How can you use thumbnails to your advantage?

Striking thumbnails with strong colors, clear imagery, high contrast and meaningful keywords bring you more clicks, because they stand out.

Using the company logo and a fixed set of color combinations again and again raises recognition and looks more professional.

How do you create a thumbnail?

Many content management systems already provide miniature versions of your content automatically. If you want to build a thumbnail yourself, programs such as Photoshop or GIMP are a good fit.

A few things are worth watching: the resolution (at least HD, 1280 x 720 pixels) and the aspect ratio (16:9, the same format used for videos).