Ultimate Guide Section 1: Image Description Essentials

Introduction to This Guide

Welcome to Scribely’s Ultimate Guide to Image Description.

At Scribely, we believe that image description is more than a checkbox. It’s a vital part of creating effective, accessible, and user-centered digital experiences. Our Ultimate Guide to Image Description is designed to be your go-to resource for understanding alt text and how to write it effectively. Whether you’re new to accessibility or a seasoned professional, this guide offers practical insights, examples, and strategies drawn from our real-world experience in remediation, consulting, and training.

Note: This is a living resource. We’re continually updating it with our latest findings and best practices to keep pace with emerging technologies and evolving standards. Be sure to check back often as we add more of our most valuable insights.

Here’s what you’ll find inside:

• Section 1: Image Description Essentials: Understand the foundations, including what alt text is, why it matters, and who benefits.
• Section 2: Core Principles and Crafting Your Description: Learn how to write clear, meaningful descriptions that prioritize context and impact.
• Section 3: Image Types and How to Describe Them: Tailored approaches for charts, infographics, decorative images, social media visuals, and more.
• Section 4: Alt Text and SEO in the Age of AI: Explore how alt text intersects with machine learning, image recognition, and search optimization.
• Section 5: Advanced Techniques and Implementation: From writing for complex visuals to scaling accessible content, this section dives into the details.

We hope this guide empowers you to create more accessible content and become a champion for digital inclusion.

What Is Alt Text?

Every image on the web carries meaning, whether it shows a product feature, illustrates data trends, or adds visual interest. For many users, those visuals can be inaccessible without a text alternative.

Alternative text, or “alt text,” appears in the HTML alt attribute and translates an image’s content into words. Alt text should capture an image’s purpose and meaning in clear, concise language. Aim to keep it under 250 characters; if you need more detail, link to an extended description elsewhere on the page. Without alt text, assistive-technology users may see only a file name (for example, image123.png) or nothing at all, missing out on important information.

• Definition: A brief, accurate description of an image’s content and purpose.
•  Technical note: Placed in the alt attribute of an <img> tag.
• Length guideline: Up to 250 characters; use a long description for complex visuals.

Why Alt Text Matters

Images add depth and clarity to digital content, but they can also create barriers when not described properly. Inaccessible images frustrate users, expose organizations to legal risks, and weaken SEO. Writing good alt text is both an ethical requirement—ensuring everyone can access your content—and a practical step to improve usability and search visibility.

1. Legal & Accessibility Compliance
   Alt text is required under the Web Content Accessibility Guidelines (WCAG 1.1), which state that all non-text content must have an equivalent text alternative. In the United States, Section 508 of the Rehabilitation Act and the Americans with Disabilities Act reference these guidelines, making alt text effectively mandatory for many websites.
2. User Experience & Inclusion
   Properly described images help blind, low-vision, DeafBlind, dyslexic, and light-sensitive users access the same information as sighted readers. A clear text description ensures no one is left guessing.
3. Technical & SEO Benefits
   If an image fails to load because of a slow connection or a broken link, alt text appears in its place, keeping content meaningful. Search engines also index alt text, which can boost your site’s ranking and drive more traffic.

Who Uses Alt Text and How

Every alt attribute supports users who rely on text to understand images. Key audiences include:

• Screen-reader users (e.g., VoiceOver on Apple devices, NVDA on Windows) hear alt text read aloud.
• Braille-display users read alt text on refreshable Braille devices.
• Language translators convert alt text into other languages during localization.
• Fallback viewers see alt text when images do not render due to connectivity or errors.

Context & Purpose: Tailoring Your Approach

Not every image serves the same role. A single strategy can either overwhelm users with too much detail or leave out critical information. Before writing alt text, ask three questions:‍

1. What is the image’s role?

• Decorative: Mark with alt="" so assistive tools skip it.
• Informative/Functional: Provide a meaningful description, for example, data trends in a chart or the action of a “Buy Now” button.

2. Where will it appear?

• Web pages allow longer alt text than character-limited social platforms.
• Print or Braille may reuse alt text as captions or standalone descriptions.

3. Who is the audience?

• Specialists may need technical terms; general readers need simpler language.
• Cultural considerations can affect how you describe symbols, colors, or expressions—use respectful, inclusive terms.

By focusing on each image’s purpose, location, and audience, you create alt text that is useful and accessible. In Section 2, we will cover a straightforward, step-by-step process for writing alt text that is clear and effective.