Why Alt text for images in HTML? - Purpose & Use Cases

The Big Idea

Discover how a few words can open your website to everyone, no matter how they browse!

The Scenario

Imagine you add pictures to your website to make it look nice. You just upload images without any description.

The Problem

People who use screen readers or have slow internet can't understand what the images show. Also, if images don't load, visitors see nothing and get confused.

The Solution

Alt text gives a short, clear description of each image. Screen readers read it aloud, and it shows if images fail to load.

Before vs After

✗ Before

<img src="flower.jpg">

✓ After

<img src="flower.jpg" alt="Red rose with dew drops">

What It Enables

Alt text makes your website friendly and clear for everyone, including people with disabilities and slow connections.

Real Life Example

A visually impaired person visits your site and hears the alt text describing each image, helping them understand your content fully.

Key Takeaways

Alt text describes images for those who can't see them.

It improves accessibility and user experience.

Adding alt text is simple but powerful for inclusivity.

Practice

1. What is the main purpose of the alt attribute in an <img> tag?

easy

A. To add a border around the image

B. To provide a text description of the image for screen readers and when the image cannot load

C. To change the image size on the webpage

D. To link the image to another webpage

Solution

1. Step 1: Understand the role of alt text

   The alt attribute gives a text description of the image content.

2. Step 2: Recognize accessibility and fallback use

   This text helps screen readers for visually impaired users and shows if the image fails to load.

3. Final Answer:

   To provide a text description of the image for screen readers and when the image cannot load -> Option B

4. Quick Check:

   Alt text = image description [OK]

Hint: Alt text describes images for accessibility and fallback [OK]

Common Mistakes:

• Thinking alt changes image size
• Using alt to add styling like borders
• Confusing alt with links

2. Which of the following is the correct way to add alt text to an image in HTML?

easy

A.

B.

C.

D.

Solution

1. Step 1: Identify the correct attribute for alt text

   The correct attribute to describe images is alt.

2. Step 2: Check the syntax of the <img> tag

   <img src="flower.jpg" alt="Beautiful red flower"> uses alt="Beautiful red flower", which is correct HTML syntax.

3. Final Answer:

   <img src="flower.jpg" alt="Beautiful red flower"> -> Option A

4. Quick Check:

   Use alt attribute for image description [OK]

Hint: Use alt="description" inside <img> tag [OK]

Common Mistakes:

• Using non-existent attributes like description or text
• Confusing alt with title attribute
• Omitting quotes around alt text

3. What will a screen reader announce for this image tag?

<img src="logo.png" alt="Company logo">

medium

A. It will say 'Company logo' aloud

B. It will ignore the image and say nothing

C. It will read the file name 'logo.png'

D. It will say 'image' only

Solution

1. Step 1: Understand screen reader behavior with alt text

   Screen readers read the alt attribute to describe images to users.

2. Step 2: Check the alt attribute content

   The alt text is "Company logo", so the screen reader will announce this phrase.

3. Final Answer:

   It will say 'Company logo' aloud -> Option A

4. Quick Check:

   Screen reader reads alt text [OK]

Hint: Screen readers read alt text, not file names [OK]

Common Mistakes:

• Assuming screen readers read image file names
• Thinking screen readers ignore images with alt
• Confusing alt with title attribute

4. Identify the error in this image tag:

<img src="photo.jpg" alt>

medium

A. The alt attribute should be written as alt-text

B. The src attribute is incorrect

C. The img tag is missing a closing tag

D. The alt attribute is missing a value

Solution

1. Step 1: Check the alt attribute syntax

   The alt attribute must have a value, like alt="description". Here it is empty without ="...".

2. Step 2: Confirm other attributes and tag correctness

   The src attribute is correct, and <img> is self-closing in HTML5, so no closing tag needed.

3. Final Answer:

   The alt attribute is missing a value -> Option D

4. Quick Check:

   Alt attribute needs a value in quotes [OK]

Hint: Alt attribute must have a quoted value [OK]

Common Mistakes:

• Leaving alt attribute empty without =""
• Thinking img needs a closing tag
• Using invalid attribute names like alt-text

5. You have a decorative image that adds no meaning to your page. How should you write the img tag for best accessibility?

hard

A.

B.

C.

D.

Solution

1. Step 1: Understand alt text for decorative images

   Decorative images should have empty alt text (alt="") so screen readers skip them.

2. Step 2: Evaluate options for accessibility

   <img src="decorative.png" alt=""> uses empty alt, which is correct. Omitting alt or using generic text causes confusion.

3. Final Answer:

   <img src="decorative.png" alt=""> -> Option C

4. Quick Check:

   Empty alt hides decorative images from screen readers [OK]

Hint: Use alt="" for decorative images [OK]

Common Mistakes:

• Omitting alt attribute entirely
• Using vague alt text like 'image' or 'decorative image'
• Adding unnecessary descriptions for decoration