Definition

alt text (alternative text)

Part of the Multimedia and graphics glossary:

Alt text (alternative text) is a word or phrase that can be inserted as an attribute in an HTML (Hypertext Markup Language) document to tell Web site viewers the nature or contents of an image. The alt text appears in a blank box that would normally contain the image. Alt text is useful when an image link is not available because of a broken or changed URL or some other issue.

An alt attribute starts out with the character sequence alt= and then contains the alt text within quotation marks. For example, the attribute alt="Storm Surge" might appear in the HTML image tag for a photograph of high water during a hurricane. In most browsers, hovering the pointer over an image containing an alt attribute will cause the alt text to appear within a small box beneath the pointer.

When choosing alt text, it's important to ensure that it tells viewers as much as possible about the image, using as few words as possible. This consideration becomes increasingly important as images get physically smaller. If the alt text is too long, it might take up too much space to fit inside the image rectangle (which is the same size as the image would be if it were visible). With bullet links that have external text labels, for example, alt text would only cause clutter. In cases of that sort, the alt text can comprise a single space between the quotes (alt=" ") or the two quotes can be placed right up against each other (alt="").

Alt attributes should always go inside image tags, even if no alt boxes are wanted. If the Web page author does not want an alt box to appear in conjunction with an image, a blank alt attribute should be inserted in the image tag to ensure that a default character sequence showing the image's Web address will not appear when the viewer hovers the pointer over the image.

Alt text is a good place to place relevant keywords to improve your website’s search engine optimization (SEO). As with text elsewhere, however, keyword stuffing -- the practice of inserting a large number of keywords into Web content -- is discouraged. According to Google, the practice is not only unethical but also ineffective.

This was last updated in October 2012
Contributor(s): Stan Gibilisco
Posted by: Margaret Rouse

Related Terms

Definitions

  • raster graphics

    - Raster graphics are digital images created or captured (for example, by scanning in a photo) as a set of samples of a given space. (WhatIs.com)

  • Mantle

    - Mantle is a low-level 3D graphics application programming interface (API) created by AMD for their graphics processing units (GPUs) based on the Graphics Core Next (GCN) architecture. Mantle incre... (WhatIs.com)

  • tablet (tablet PC)

    - A tablet is a wireless, portable personal computer with a touch screen interface. The tablet form factor is typically smaller than a notebook computer but larger than a smartphone. (SearchMobileComputing.com)

Glossaries

  • Multimedia and graphics

    - Terms related to multimedia, including graphics, animation and video definitions and words and phrases about images and sound.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question. Find an Answer.Powered by ITKnowledgeExchange.com

Ask An IT Question

Get answers from your peers on your most technical challenges

Ask Question

Tech TalkComment

Share
Comments

    Results

    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.