Image Alt Text for SEO: Why and How
Alt text (alternative text) is a crucial yet often overlooked element of web optimization. It serves a dual purpose: enhancing search engine optimization (SEO) and improving website accessibility for visually impaired users.
In this blog, we’ll explore the significance of image alt text, how it impacts SEO and accessibility, and the best practices for writing effective alt text that benefits both users and search engines.
Defining Image Alt Text
Image alt text is a short textual description added to the HTML code of an image. Its primary function is to describe an image’s content to search engines and assistive technologies like screen readers used by visually impaired individuals
When an image fails to load, the alt text appears in its place, ensuring that users still understand the image’s context.
By properly defining images, websites become more accessible and optimized for search engines.
Importance for SEO
Search engines like Google cannot "see" images the way humans do. Instead, they rely on alt text to understand an image’s relevance and context. Here’s how alt text impacts SEO:
Improves Search Rankings - Well-optimized alt text helps search engines index images correctly, making them appear in Google Images search results and improving website visibility.
Enhances User Experience - When images fail to load due to a slow connection, alt text provides valuable context, reducing frustration for users.
Boosts Website Traffic - Optimized images with descriptive alt text can appear in Google Image searches, driving additional organic traffic to your website.
Supports Voice Search Optimization - With the rise of voice search, properly written alt text can enhance a website’s chances of being found via voice-activated search queries.
Encourages Backlinks & Social Sharing - When images are properly indexed, they have a higher likelihood of being shared or linked by other websites, further improving domain authority.
Improves E-Commerce Performance - Product images with relevant alt text can appear in Google Shopping results, leading to increased conversions for online retailers.
Helps Image-Based AI & Search Features - Google’s AI-driven search features increasingly rely on image recognition. Alt text helps contextualize visuals, ensuring they are matched with relevant search queries.
Benefits for Accessibility
Alt text plays a crucial role in web accessibility, ensuring that users with visual impairments can understand the content of images using screen readers.
Enhances User Inclusivity - Alt text makes digital content more inclusive by allowing visually impaired users to consume image-based information.
Compliance with Web Accessibility Standards - Many web accessibility regulations, including the Web Content Accessibility Guidelines (WCAG) and the Americans with Disabilities Act (ADA), require websites to include meaningful alt text.
Better User Engagement - By making content more accessible, websites improve user satisfaction and retention, leading to a better overall experience.
Crucial for Assistive Technologies - Screen readers read out alt text to visually impaired users, ensuring they fully understand the images present on a webpage.
Improves Usability for All Users - Users in low-bandwidth areas or those with slow-loading connections benefit from alt text when images fail to load.
Supports Multimodal Access - Some users rely on text-to-speech tools even if they are not visually impaired. Alt text ensures these users receive a complete experience.
Reduces Legal Risks - Non-compliance with accessibility guidelines can result in lawsuits or penalties, making proper alt text an essential aspect of website maintenance.
Best Practices & How to Write Effective Alt Text
Writing effective alt text requires a balance between clarity, conciseness, and on-page SEO optimization. Follow these best practices:
Be Descriptive and Specific - Clearly describe the image's content while keeping it relevant. Example (Good):
alt="Golden retriever puppy playing with a red ball on green grass". Example (Bad):alt="Dog playing".Include Keywords Naturally - Use relevant keywords without stuffing them unnaturally. Example:
alt="Organic cotton tote bag with sustainable design".Keep It Concise - Aim for 125 characters or less. Screen readers may truncate longer descriptions.
Avoid Redundant Phrases - Do not use phrases like "image of" or "picture of," as screen readers already announce images.
Maintain Context - The alt text should match the surrounding content and page purpose.
Common Mistakes & Pitfalls
Avoid these common mistakes that can diminish the effectiveness of alt text:
Keyword Stuffing - Overloading alt text with keywords can make it unreadable and negatively impact SEO. Example:
alt="cheap running shoes best price discount sale online shopping".Vague or Generic Descriptions - Descriptions like "image123" or "logo" do not provide any meaningful context.
Overly Long Alt Text - Lengthy descriptions may be cut off by screen readers and lose effectiveness.
Missing Alt Text Altogether - Skipping alt text entirely reduces accessibility and search visibility.
Repeating the Same Alt Text for Different Images - Each image should have a unique description relevant to its content.
Describing the Image Rather than Its Function - If an image serves a purpose (e.g., a CTA button), describe the function rather than the appearance. Example:
alt="Download our free eBook"instead ofalt="Green button with white text".Relying on AI-Generated Alt Text Without Review - Some automated tools generate inaccurate or irrelevant alt text, which can lead to misleading descriptions.
Technical Implementation & Tools
Adding alt text varies by CMS and website platform. Here’s how to do it on some popular platforms:
WordPress - While uploading an image to the Media Library, enter the alt text in the "Alternative Text" field.
Shopify - Go to "Products" → "Media" → "Edit image alt text".
Wix - Click on an image, then select "Settings" to add alt text.
HTML Manual Entry -Add alt text directly in the HTML code as shown earlier.
Useful Tools:
Google Lighthouse (for accessibility audits)
FAQs
1. Should every image have alt text?
Yes, every image must have an alt text.
2. Can I use the same alt text for multiple images?
No, each image should have a unique alt text relevant to its specific content.
3. Does alt text help social media images?
Yes, platforms like X and Instagram allow alt text to improve accessibility and engagement.
4. How does Google penalize bad alt text practices?
Keyword stuffing, missing alt text, and irrelevant descriptions can negatively impact SEO rankings.
Conclusion and Next Steps
Optimizing image alt text is essential for improving SEO performance and ensuring website accessibility. By following best practices—being descriptive, concise, and contextually relevant—you can enhance user experience, drive organic traffic, and comply with accessibility guidelines.
Next steps:
Audit your website images - to identify missing or poorly optimized alt text.
Use SEO and accessibility tools - to test and improve your alt text.
Continuously update - image descriptions to keep them relevant and effective.
By prioritizing alt text, you create a more inclusive and search-friendly website that benefits all users. Start optimizing today!
