Alt Text

Definition

Alt text (alternative text) is a written description added to an image's HTML that tells search engines and screen readers what the image depicts, improving both SEO and web accessibility. It appears in image tags as . Search engines cannot see images the way humans do, so alt text is how they understand what an image contains. It also displays in place of the image if the image fails to load, and is read aloud by screen readers for visually impaired users.

How It Works

Alt text should describe the image accurately and concisely. For SEO purposes, it is also an opportunity to include relevant keywords where they fit naturally. The rule is: write for the person who cannot see the image. Describe what is actually in the image, what it shows, and ideally how it relates to the page's subject matter.

Poor alt text is generic ("image1.jpg" or "photo"), stuffed with keywords without describing the image ("plumber Chicago plumbing service Chicago pipes"), or entirely absent. Good alt text is specific and natural: "licensed plumber replacing copper pipes under kitchen sink in Lincoln Park home."

Why It Matters

Every image on your site without alt text is a missed opportunity for search signals and a barrier for visually impaired users. For businesses that rely on portfolio images, product photos, or location photos, alt text is a direct signal about what those images show and where they are located. Image search is also a real source of traffic. A roofing company with well-described images of their work can appear in Google Image Search for "roof replacement [city]" and drive additional leads.

Example

A landscape design company has 80 portfolio photos on their website with no alt text. After writing specific alt text for each image describing the plant species, design style, neighborhood, and project type, Google begins indexing the images in image search. The company starts receiving inquiries from homeowners who found them through image searches for specific landscaping styles in their area.

Related Terms

On-Page SEO, Technical SEO, Schema Markup, Keyword Research, Structured Data

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