Images make content more engaging, memorable, and visually appealing—but without proper descriptions, they can become invisible to both users and search engines. This is where alt text comes in.
Alt text, short for “alternative text,” plays a crucial role in helping search engines understand images and ensuring accessibility for users who rely on screen readers. Despite its importance, many websites either ignore it or use it incorrectly, leaving valuable opportunities untapped.
This guide will walk you through everything you need to know about alt text—what it is, why it matters, how to write it effectively, and how to avoid common mistakes. Whether you’re a beginner or looking to refine your approach, you’ll find practical, actionable insights here.
What Is Alt Text? (Quick Answer)
Alt text is a short written description added to an image’s HTML code. It describes the content and purpose of the image for users who cannot see it and helps search engines understand what the image represents.
Why Alt Text Matters
Alt text is not just a technical detail—it serves multiple important purposes that directly impact user experience and visibility.
Accessibility for All Users
Alt text ensures that visually impaired users can understand images through screen readers. Without it, a key part of your content becomes inaccessible.
Better Image Understanding
Search engines cannot “see” images the way humans do. Alt text provides context, helping them understand what the image contains and how it relates to the surrounding content.
Improved Page Relevance
When used correctly, alt text reinforces the topic of your page. It supports the overall message and adds another layer of clarity.
Fallback for Broken Images
If an image fails to load, the alt text appears in its place, giving users context instead of leaving a blank space.
How Alt Text Works
Alt text is added within the image tag in HTML. For example:
<img src="dog.jpg" alt="Golden retriever playing in the park">
This simple line tells browsers and assistive technologies exactly what the image shows.
Behind the scenes, screen readers read this description aloud, while search engines use it to index the image.
How to Write Effective Alt Text
Writing good alt text is both an art and a skill. It requires clarity, relevance, and precision.
Be Descriptive but Concise
Describe what’s in the image clearly, but avoid unnecessary detail.
Good example:
“A red apple on a wooden table”
Bad example:
“A shiny, bright red apple sitting beautifully on a rustic wooden table in natural sunlight with a blurred background”
Focus on What Matters
Think about the purpose of the image. What should the user understand from it?
If the image supports a point, describe that point—not every visual detail.
Use Natural Language
Write alt text like a human would speak. Avoid awkward phrasing or forced keywords.
Include Context When Necessary
If the image relates to the surrounding content, reflect that connection.
For example, if an image shows a step in a tutorial, describe the action being performed.
Avoid Redundant Phrases
Do not start with phrases like “image of” or “picture of.” Screen readers already identify images.
Instead of:
“Image of a mountain landscape”
Write:
“Mountain landscape with snow-covered peaks”
Keep It Short
Aim for clarity within one sentence. Most alt text should be under 125 characters.
Examples of Good vs Bad Alt Text
Example 1: Product Image
Bad:
“Shoes”
Good:
“Black running shoes with white soles”
Example 2: Informational Image
Bad:
“Chart”
Good:
“Bar chart showing sales growth from 2020 to 2025”
Example 3: Decorative Image
If an image is purely decorative and adds no meaning, use empty alt text:
alt=""
This tells screen readers to skip it.
Types of Images and How to Handle Them
Different types of images require different approaches.
Informational Images
These include charts, diagrams, and infographics. Focus on the key message or insight.
Product Images
Describe the product clearly, including important features like color, size, or style.
Functional Images
Icons or buttons should describe their function, not appearance.
Example:
“Search” instead of “magnifying glass icon”
Decorative Images
If the image has no meaningful purpose, leave the alt text empty.
Important Points People Often Overlook
Many people understand the basics but miss these critical details.
Context Is Everything
The same image can require different alt text depending on where it appears.
For example, a photo of a laptop could be described differently on a tech review page versus a remote work blog.
Don’t Repeat Nearby Text
If the surrounding content already explains the image, avoid repeating it word-for-word.
Captions and Alt Text Are Not the Same
Captions are visible to users. Alt text is primarily for accessibility and background understanding. They can complement each other but serve different purposes.
Avoid Keyword Stuffing
Stuffing alt text with keywords makes it unnatural and less useful. Focus on clarity first.
Common Mistakes and Misconceptions
Even experienced creators often make these errors.
Writing Too Much
Overly long descriptions can confuse users and reduce clarity.
Being Too Vague
Short doesn’t mean meaningless. “Image” or “photo” provides no value.
Ignoring Alt Text Completely
Many websites skip alt text altogether, missing both accessibility and visibility benefits.
Using the Same Alt Text Repeatedly
Each image should have unique alt text based on its specific content and role.
Describing What Isn’t Relevant
If the image supports a specific idea, focus on that—not unrelated details.
Alt Text vs Title Attribute: What’s the Difference?
These two are often confused but serve different roles.
Alt text is essential for accessibility and image understanding. It appears when images fail to load and is read by screen readers.
The title attribute, on the other hand, appears as a tooltip when users hover over an image. It is not a replacement for alt text and should not be relied on for accessibility.
Step-by-Step Process to Write Alt Text
If you’re unsure how to approach it, follow this simple process:
Step 1: Look at the Image
Ask yourself: What is the main subject?
Step 2: Identify Its Purpose
Why is this image here? What does it add to the content?
Step 3: Describe the Key Information
Write a short, clear sentence describing the image’s most important aspect.
Step 4: Keep It Natural
Read it aloud. Does it sound like something a human would say?
Step 5: Check for Redundancy
Make sure you’re not repeating nearby text unnecessarily.
Practical Tips and Best Practices
Small improvements can make a big difference.
Write alt text as if you’re explaining the image to someone over the phone.
Focus on clarity over cleverness. Simplicity always wins.
Use specific details when they matter, such as colors, actions, or key features.
Keep consistency across your website, especially for similar types of images.
Review and update alt text regularly, especially when updating content.
FAQs
What is the ideal length for alt text?
Most alt text should be under 125 characters. The goal is to be concise while still providing meaningful information.
Should every image have alt text?
Yes, but not all alt text should contain descriptions. Decorative images should use empty alt text (alt="") so screen readers skip them.
Can alt text improve rankings?
Alt text helps search engines understand images and content context, which can indirectly improve visibility and relevance.
Is it okay to include keywords in alt text?
Yes, but only if they fit naturally. Forced or excessive keyword use reduces clarity and effectiveness.
How is alt text different from image captions?
Alt text is primarily for accessibility and background understanding, while captions are visible text meant for all users.
Conclusion
Alt text may seem like a small detail, but it carries significant impact. It improves accessibility, enhances content clarity, and helps search engines better understand your images.
The key is to write alt text that is clear, relevant, and purposeful. Focus on describing what matters, keep it natural, and always consider the user experience.
When done right, alt text doesn’t just support your content—it strengthens it.
