Alt text for images in HTML - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is alt text in an image tag?

alt text is a short description of an image used in HTML to help people who cannot see the image understand what it shows.

beginner

Why is alt text important for web accessibility?

It helps screen readers describe images to users who are blind or have low vision, making the web more inclusive.

beginner

How do you add alt text to an image in HTML?

Use the alt attribute inside the <img> tag, like this: <img src="photo.jpg" alt="A smiling dog">.

beginner

What should you write in alt text?

Write a clear, simple description of the image’s content or purpose. Avoid phrases like "image of" or "picture of".

intermediate

When should alt text be left empty (alt="")?

When the image is purely decorative and does not add meaning, leaving alt="" tells screen readers to skip it.

What does the alt attribute do in an <img> tag?

A Links the image to another page

B Provides a text description of the image

C Adds a border around the image

D Changes the image size

The alt attribute gives a text description of the image for accessibility and when images don’t load.

Which is a good example of alt text for a photo of a red apple?

A "Fruit"

B "Image of a red apple"

C "Red apple on a wooden table"

D "Picture"

Option C describes the image clearly and meaningfully without unnecessary words.

When should you use alt="" (empty alt text)?

A For decorative images

B For images with text

C For important images

D Never use empty alt text

Empty alt text tells screen readers to ignore decorative images that don’t add information.

What happens if you forget to add alt text to an image?

A The image will be clickable

B The image won’t show

C The page will load faster

D Screen readers may read the image file name, which can be confusing

Without alt text, screen readers may read the file name, which is often not helpful.

Which HTML is correct for an image with alt text?

A <img src="dog.jpg" alt="A happy dog">

B <img alt="A happy dog" src="dog.jpg">

C <img src="dog.jpg">

D <img alt>A happy dog</img>

Option A correctly uses the alt attribute inside the <img> tag.

Explain why alt text is important for images on websites.

Think about users who cannot see images.

Describe how to write good alt text for an image.

Imagine explaining the image to a friend who can’t see it.

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