What is a Thumbnail Image?

R. Kayne

A thumbnail image is a small graphics file. These images are created from standard size images and are used on webpages. The small size allows Web surfers quick access to webpage content. Dial-up users would find retail shopping nearly impossible if it weren’t for the use of thumbnail images, and surfing pages with multiple images would simply take too long.

Thumbnail images allow more content to be shown on a screen.
Thumbnail images allow more content to be shown on a screen.

In many cases, thumbnail images are clickable, causing a larger image to load at the user’s discretion. This makes webpages user-friendly, saving the surfer from having to download large image files that he or she doesn’t need or want to see. With a page of smaller images, the user can click on only those images of interest.

Thumbnail images often are clickable, which leads to a larger image loading on the screen.
Thumbnail images often are clickable, which leads to a larger image loading on the screen.

Webpages are written in Hypertext Markup Language (HTML). Web browsers translate this text-based HTML code into the graphical display seen as webpages. In most cases, creating a thumbnail image with an HTML editor is no more complicated than choosing to insert an image file into a webpage, then clicking on a few dialog boxes to create the small image from the original.

The thumbnail image can also be resized within the editor, and have custom “mouseover text” assigned to it. If so, a small text box will pop up when a surfer runs the mouse pointer over the image. The mouseover text might describe the thumbnail, or it might say, “Click me for a larger view.” A webmaster might also choose to assign funny captions to thumbnails using the mouseover option.

When images are created using an HTML editor, the software will create the smaller file from the larger file, using the same file format. For example, if the original file is a .jpg file, the thumbnail will be a much smaller .jpg file. If the original is a .gif file, the thumbnail will also be a .gif file. The HTML editor will insert the newly created small image into the webpage and give the user a choice to create a link to the original, larger image. This will make the thumbnail clickable.

While many people who surf the Internet are switching from slower dial-up accounts to faster Digital Subscriber Line (DSL) and cable Internet Service Providers (ISPs), thumbnails still save surfers valuable time. They also allow webmasters to fit more content on a webpage, minimizing the need for scrolling. Online retail storefronts and auction sites make frequent use of thumbnail images to show their wares. Art galleries, personal photo galleries, news hubs, and social hubs all use these small images as well.

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Discussion Comments


How do people make the moving thumbnail photos? I'm not sure what they're called but I see them all the time as people's profile pictures. I think they make them from videos. They're very cool.


@ankara-- Yea, that happens often. A thumbnail image can only be up to a certain size. It usually has to be less than 180,000 bytes.

You need to re-size the image into a smaller one. Just open the image in any program and re-size it. After saving the image, you can right-click on the image and click properties. In the properties, you will be able to see the size of the image in bytes. If it is still too large, re-size it once again and save it.

Sometimes, a website thumbnail can only be in .png or .jpeg format. If the image is in a different format, you might have to re-save it in one of the accepted formats. These options are available when you go to "save image as."


I'm trying to upload an image as my thumbnail image on a forum. But I keep getting a message saying that the file is too large. What do I need to do?


Another advantage of thumbnails is that they save viewing space on your computer. As the @frogfriend mentioned, you can drag and drop a thumbnail file, or you can also hover on a thumbnail file and use the secondary mouse button to choose a command such as cut and paste, to move the file to where you want it.


As a photographer I always thought that thumbnail images were simply too small for any good use on the screen. It is obvious now that my thoughts were far from what most people can enjoy while looking at pictures on a computer.

Amazingly I now use thumbnail files to sort through my entire collection of photographs from years past. It is much easier to drag and drop thumbnail files instead opening a file name every time I want to organize.

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