Alt Text
Descriptive text associated with an image that explains the image's content to search engines and screen readers. Alt text improves accessibility and provides an SEO ranking signal for image search.
What is Alt Text?
Alt text (alternative text) is a brief, descriptive phrase attached to images via the alt attribute in HTML code. It serves two critical purposes: it displays when images fail to load (providing context to users), and it describes image content to search engines and assistive technologies like screen readers. For users with visual impairments, alt text is essential—screen readers rely entirely on alt text to communicate what an image contains.
Effective alt text is concise (typically 100-125 characters) yet descriptive enough to convey the image's purpose and content. Rather than generic descriptions like 'photo' or 'image,' quality alt text includes relevant context. For example, instead of 'shoes,' write 'women's running shoes in blue and white' or 'Nike Air Zoom Pegasus 40 running shoe, white model with blue accents.' When images are buttons or links, alt text should describe the action or destination, not just the visual appearance.
From an SEO perspective, alt text provides search engines with text-based information about images, helping them understand content context and enabling your images to rank in Google Images. This is particularly valuable for image-heavy sites like e-commerce, fashion, or food blogs where image search traffic can represent 20-40% of total organic traffic. Google's algorithms use alt text alongside page content, image analysis, and image filename to understand image relevance to search queries.
Writing alt text shouldn't feel like optimizing for algorithms—it should reflect the genuine purpose and content of the image. Natural language with relevant keywords works best because alt text that feels forced or keyword-stuffed appears unprofessional and may trigger spam detection.
Why It Matters for SEO
Alt text signals page relevance to search engines, particularly for image-heavy content. Comprehensive alt text across your site improves accessibility (ethical obligation plus Google's emphasis on user experience), increases chances of ranking in Google Images, and enhances content comprehensiveness for regular search results. For e-commerce sites, product image alt text directly impacts discoverability—images with quality alt text rank in image search, driving qualified traffic.
Examples & Code Snippets
Basic Product Alt Text
<img src="nike-shoes.jpg" alt="Nike Air Zoom Pegasus 40 women's running shoe in white with blue accents">Descriptive alt text that includes product name, type, gender, and color attributes.
Blog Post Chart Alt Text
<img src="seo-traffic-graph.png" alt="Line graph showing organic traffic growth from January 2024 to December 2024, with a 150% increase">For charts and graphs, describe what the visual shows including the data relationship or trend.
Decorative Image Alt Text
<img src="divider.png" alt="" role="presentation">For purely decorative images, use an empty alt attribute to tell screen readers to skip the image.
Include your primary or semantic keyword naturally in alt text for your most important images, but avoid keyword stuffing. For product pages, put product names and key attributes in alt text; for blog posts, write alt text that explains how images support your topic.
Frequently Asked Questions
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