What is alt text?
Alt text is a written HTML attribute that describes the content and function of an image, helping screen reader users and search engines understand what the image shows.
Why alt text exists
Alt text is set with the alt attribute on an image element and provides a text alternative for people who cannot see the image. Screen readers read it aloud, and browsers display it when an image fails to load, making it a core accessibility feature.
Because search engines cannot fully interpret pixels, alt text also gives them a description of what an image depicts. This helps images appear in image search and adds relevant context to the surrounding page content.
Writing good alt text
Effective alt text describes the image concisely and in context, conveying the information a sighted user would gain at a glance. It should capture the meaning that matters for the page rather than listing every visual detail.
Avoid keyword stuffing, which harms both accessibility and quality. Include a relevant keyword only when it naturally describes the image, and keep the wording short and human-readable.
Decorative versus meaningful images
Purely decorative images that add no information should use an empty alt attribute so screen readers skip them, preventing needless noise for assistive technology users. This keeps the experience clean and focused on meaningful content.
Images that convey information, act as links, or contain text need descriptive alt text so their purpose is not lost. Distinguishing decorative from meaningful images is the key judgment when writing alt text.
Frequently asked questions
Does alt text help SEO?
Yes, alt text helps search engines understand images, supports image search visibility, and adds relevant context to a page, while its primary purpose remains accessibility.
Should decorative images have alt text?
Decorative images should use an empty alt attribute so screen readers skip them, while images that convey information or act as links need descriptive alt text.
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